RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                          HELIX TECHNOLOGY CORPORATION
 
 
         HELIX  TECHNOLOGY  CORPORATION,  a  corporation  organized and existing
under the laws of the State of Delaware, hereby certifies as follows:
 
         1. The name of the Corporation is HELIX TECHNOLOGY CORPORATION, and the
name  under  which  the   Corporation   was  originally   incorporated   is  500
INCORPORATED.
 
         The date of filing its original  Certificate of Incorporation  with the
Secretary of State was March 30, 1967.
 
         2.  This  Restated  Certificate  of  Incorporation  only  restates  and
integrates  and does not further  amend the  provisions  of the  Certificate  of
Incorporation of the Corporation as heretofore amended or supplemented and there
is no discrepancy  between those  provisions and the provisions of this Restated
Certificate of Incorporation.
 
         3.  The  text  of the  Certificate  of  Incorporation,  as  amended  or
supplemented,  is hereby restated without further  amendments or changes to read
as follows:
         FIRST.  The name of the Corporation is HELIX TECHNOLOGY CORPORATION.
 
         SECOND.  Its  registered  office in the State of Delaware is located at
No. 100 West Tenth Street, in the City of Wilmington,  County of New Castle. The
name and address of its registered agent is The Corporation  Trust Company,  No.
100 West Tenth Street, Wilmington, Delaware.
 
         THIRD.  The nature  of  the  business,  or  objects  or  purposes to be
transacted, promoted or carried on are:
 
         To engage in the  manufacture,  sale and  other  disposition of devices
for the production of refrigeration and/or the liquefication or solidifaction of
gases for the  purification of gases, for the production and maintenance of high
vacuums,  and for the production of extremely high  temperatures  for scientific
and  technical  purposes,  including  the growing of crystals.  To engage in the
manufacture and sale of scientific and technical equipment,  and the purchase or
manufacture  and  sale  of  accessory  materials,  equipment  and  supplies.  To
undertake,  the  installation  and  trial  operation  of  such  devices  and the
instruction  of others in the  operation  of such  devices and to perform  other
professional and technical services.
 
         To engage in engineering,  research and development for its own account
or for the  account  of others  in any field of  science  or  knowledge  pure or
applied.
<PAGE>
 
         To carry on a general manufacturing and merchandising  business and any
business incidental thereto or in any way connected  therewith,  including,  but
without limiting the generality of the foregoing purpose,  the trade or business
of preparing,  processing,  producing,  manufacturing,  adapting,  synthesizing,
forming, treating, finishing, converting,  experimenting, testing, and otherwise
acquiring,  owning,  holding,  consuming,  disposing  of and dealing in and with
interests in metals, minerals, and other materials,  substances or compounds, or
combinations  thereof,  organic and inorganic,  natural or  artificial,  and the
invention, design and fabrication of tools, apparatus and equipment employing or
useful for the  employing  of any such  materials,  and any and all other goods,
articles,  materials,  equipment,  compounds  or  substances  required  for,  or
convenient in connection  with or  incidental to any of the  foregoing;  and any
other trade or business which can conveniently be carried on in conjunction with
any of the  matters or  purposes  aforesaid  or in or upon the  premises  of the
corporation.
 
         To acquire,  hold, use, sell, assign,  lease, grant licenses in respect
of mortgage or otherwise  dispose of letters  patent of the United States or any
foreign country, patent rights, licenses and privileges,  formulas,  inventions,
improvements and processes,  trade secrets,  trademarks and trade names relating
to or useful in connection with any business of the corporation.
 
         In general,  to carry on any or all of the business of the  corporation
as principal, agent or contractor, and to carry on any other business incidental
to and in connection  with the foregoing and to have and exercise all the powers
conferred by laws of Delaware  upon  corporations  formed under the  Corporation
Laws of the State of Delaware.
 
         FOURTH.
 
         (a) The  total  number of shares  of stock  which  the  corporation  is
authorized  to issue is  7,000,000,  of which  5,000,000  shares shall be common
stock,  par  value of $1 per  share  ("Common  Stock")  and  2,000,000  shall be
preferred stock, par value $1 per share ("Preferred Stock").
 
         (b) Preferred  Stock may be issued,  from time to time, by the Board of
Directors as herein provided, in one or more series. The designations,  relative
rights,  preferences and limitations of the Preferred Stock, and particularly of
the shares of each series thereof, may be similar to or may differ from those of
any other series.  The Board of Directors of the corporation is hereby expressly
granted  authority,  subject to the provisions of this Article FOURTH, to divide
and issue,  from time to time, any or all of the Preferred  Stock in one or more
series  and to fix,  from time to time,  before  issuance  thereof,  by filing a
certificate  pursuant to the General  Corporation  Law of the State of Delaware,
the  number of shares in each such  series of such  class and all  designations,
relative rights (including the right to convert into shares of any class or into
shares of any series of any class), preferences and limitations of the shares in
each  such  series,  including  but  without  limiting  the  generality  of  the
foregoing, the following:
 
 
<PAGE>
 
                  (i)      The number of shares to constitute such series (which
                           number  may at any  time,  or from  time to time,  be
                           increased  or  decreased  by the Board of  Directors,
                           notwithstanding  that  shares  of the  series  may be
                           outstanding at the time of such increase or decrease,
                           unless the Board of  Directors  shall have  otherwise
                           provided in creating  such series,  but shall only be
                           decreased  to a  number  not  less  than  that of the
                           shares  of  such  series  then  outstanding)  and the
                           designation thereof;
 
                  (ii)     The  dividend  rate or  rates on the  shares  of such
                           series   and   any   restrictions,   limitations   or
                           conditions  upon the payment of such  dividends,  and
                           whether or not dividends on the shares of such series
                           shall be cumulative,  and the date or dates,  if any,
                           from which  dividends  thereon shall cumulate and the
                           dates  on  which  dividends,  if  declared,  shall be
                           payable;
 
                  (iii)    Whether  or not the  shares of such  series  shall be
                           redeemable,  and,  if  redeemable,  the date or dates
                           upon which or after  which they shall be  redeemable,
                           the amount or amounts  per share  payable  thereon in
                           the case of the redemption thereof,  which amount may
                           vary at  different  redemption  dates or otherwise as
                           permitted by law, and the other terms and  conditions
                           on which the shares may be redeemed;
 
                  (iv)     The  rights,  if any,  of holders  of such  series to
                           convert  the  same  into,  or  exchange  the same for
                           Common  Stock or other stock as permitted by law, and
                           the   price  or  prices  or  the  rate  or  rates  of
                           conversion  and the other  terms and  conditions,  if
                           any,  of  such  conversion  or  exchange,  as well as
                           provisions  for adjustment of the price or conversion
                           rate in such events as the Board of  Directors  shall
                           determine;
 
                  (v)      The  amount  per share  payable on the shares of such
                           series  in the  event  of  voluntary  or  involuntary
                           liquidation,   dissolution   or  winding  up  of  the
                           corporation;
 
                  (vi)     Whether the shares of such series shall be subject to
                           the  operation of a purchase,  retirement  or sinking
                           fund and, if so, the terms and conditions thereof;
 
                  (vii)    Whether the  holders of shares of such  series  shall
                           have voting  power,  full or limited,  in addition to
                           the  voting  powers  provided  by  law,  and in  case
                           additional  voting  powers are  accorded,  to fix the
                           extent thereof; and
<PAGE>
 
                  (viii)   Generally to fix the other rights and  privileges and
                           any  qualifications,  limitations or  restrictions of
                           such rights and privileges of such series,  provided,
                           however,    that   no   such   rights,    privileges,
                           qualifications,  limitations or restrictions shall be
                           in conflict with the Certificate of  Incorporation of
                           the corporation or with the resolution or resolutions
                           adopted  by the Board of  Directors,  as  hereinabove
                           provided,  providing  for the issue of any series for
                           which there are shares then outstanding.
 
         All shares of Preferred  Stock of the same series shall be identical in
all respects, except that shares of any one series issued at different times may
differ as to dates,  if any, from which dividends  thereon may  accumulate.  All
shares of  Preferred  Stock of all  series  shall be of equal  rank and shall be
identical in all  respects  except that to the extent not  otherwise  limited in
this Article  FOURTH any series may differ from any other series with respect to
any  one  or  more  of  the  designations,   relative  rights,  preferences  and
limitations (including,  without limitation, the designations,  relative rights,
preferences and  limitations  described or referred to in  subparagraphs  (i) to
(viii) inclusive above) which may be fixed by the Board of Directors pursuant to
this subparagraph (b).
 
         (c) The  Board of  Directors  adopted a  resolution  on June 5, 1978 as
follows:
 
         RESOLVED,  that there be and hereby is established and created a series
of preferred  stock of the  corporation  consisting of 200,000 shares having the
following  designation,   voting  powers,   relative  rights,   preferences  and
limitations:
 
1.  Designation.  Such series shall be designated "$.70  Cumulative  Convertible
Preferred Stock" (herein referred to as "$.70 Preferred  Stock").  The number of
shares of such series which may be issued shall be 200,000.
 
2.  Cumulative Dividend Rights; Restrictions on Parity Stock Payments and Junior
Stock Payments.
 
         2.1.  Cumulative  Dividend  Rights.  The holders of the $.70  Preferred
Stock  shall be  entitled  to  receive,  when and as  declared  by the  Board of
Directors,  out of funds  legally  available  for the purpose,  cumulative  cash
dividends at the rate of $.70 per share per annum,  payable quarterly on January
15,  April  15,  July 15 and  October  15 in each  year.  Dividends  on the $.70
Preferred  Stock  shall  be  cumulative  from the  dividend  payment  date  next
preceding the date on which the $.70 Preferred Stock is issued. Accumulations of
dividends shall not bear interest.
 
         2.2.  Restrictions  on Parity Stock Payments and Junior Stock Payments.
So long as any of the $.70 Preferred Stock is outstanding, the corporation shall
not at any time directly or indirectly  declare,  order,  pay, make or set apart
any sum or  property  for any  Parity  Stock  Payment or Junior  Stock  Payment,
unless, in each case,
 
                  (a) Full Cumulative  Dividends on the $.70 Preferred Stock for
         all past  Dividend  Periods and for the then  current  Dividend  Period
         shall have been declared and paid or a sum in cash  sufficient  for the
         payment thereof set apart for payment; and
 
<PAGE>
 
                  (b) the full  amount  of all  redemptions  then and  therefore
         required to be made in respect of the $.70 Preferred  Stock pursuant to
         sections 4.1 and 4.3 hereof shall have been made.
 
3.       Liquidation Rights.
 
         3.1.  Liquidations  Preferences.  In  the  event  of  any  liquidation,
dissolution or winding up of the corporation, before any payment or distribution
of the assets of the corporation  (whether  capital or surplus) shall be made to
or set apart for the  holders  of any  Junior  Stock,  the  holders  of the $.70
Preferred  Stock shall be entitled to the payment in cash of $10.00 per share if
such liquidation,  dissolution or winding up shall be involuntary, or $15.00 per
share if such  liquidation,  dissolution  or  winding  up  shall  be  voluntary,
together in each case with a sum equal to Full Cumulative  Dividends  thereon to
the date of final distribution to the holders of the $.70 Preferred Stock.
 
         3.2.  Distribution  on  Liquidation.  If,  upon  any  such  liquidation
dissolution or winding up, the assets of the corporation distributable among the
holders of the $.70 Preferred Stock shall be insufficient to pay to them in full
the  preferential  amounts  specified above,  then such assets,  or the proceeds
thereof,  shall be  distributed  among the holders of the $.70  Preferred  Stock
ratably  in   proportion  to  the  amounts  which  would  be  payable  to  them,
respectively, if such preferential amounts were paid to them in full.
 
4.       Required and Optional Redemptions.
 
         4.1.  Required  Redemptions.  On  June  1,  1989  and  on  each  June 1
thereafter  until all of the $.70 Preferred Stock shall have been redeemed,  the
corporation  shall  redeem  the  number of shares  of the $.70  Preferred  Stock
specified in the following table (subject, however, to the provisions of section
4.3  hereof),  upon the payment in cash of an amount  equal to $10.00 per share,
together  with a sum equal to Full  Cumulative  Dividends on the $.70  Preferred
Stock being redeemed to the date of redemption:
 
                                                              Number of Shares
Date of Redemption                                            to be Redeemed
 
 June 1, 1989                                                 45,000
 June 1, 1990                                                 40,000
 June 1, 1991                                                 40,000
 June 1, 1992                                                 40,000
 June 1, 1993                             All shares then remaining outstanding.
 
 
No redemption of less than all of the  outstanding  shares of the $.70 Preferred
Stock pursuant to section 4.2 hereof, and no redemption  pursuant to section 4.3
hereof of a larger  number of shares than that  specified  in this  section 4.1,
shall be credited to, or otherwise  relieve the corporation of its obligation to
make, the redemptions provided for in this section 4.1.
<PAGE>
 
         4.2.  Optional  Redemptions.  At any  time or from  time to time  after
November 30, 1981 the corporation may, at its option, upon notice as provided in
section 4.4 hereof, and subject to the provisions of section 4.3 hereof,  redeem
any (a  multiple  of 100  shares  and a minimum  of 1,000  shares) or all of the
shares of the $.70 Preferred Stock then outstanding, upon the payment in cash of
an  amount  equal  to  $10.00  per  share,  together  with a sum  equal  to Full
Cumulative  Dividends on the $.70 Preferred  Stock being redeemed to the date of
redemption,  provided  that the  corporation  shall not redeem any shares of the
$.70 Preferred Stock under this section 4.2 if the holder thereof shall elect to
convert the same in accordance  with section 5 hereof,  and  provided,  further,
that no redemption may be made under this section 4.2 unless
 
                  (a) the Market Price of the corporation's Common Stock on each
         trading  day  during  the  period of 45  consecutive  days  immediately
         preceding the date fixed for such  redemption  shall have been at least
         equal to 150% of the  Conversion  Price  (computed in  accordance  with
         section 5 hereof)  in  effect as of the close of  business  on the last
         full business day next preceding such date, and
 
                  (b) on the date fixed for such redemption the shares of Common
         Stock issuable upon conversion pursuant to section 5 hereof of the $.70
         Preferred Stock to be so redeemed shall have been registered  under the
         Securities Act, at the expense of the corporation,  pursuant to section
         10.5  of the  Purchase  Agreements  dated  May  31,  1978  between  the
         corporation and certain  institutional  investors  relating to the $.70
         Preferred  Stock (the  "Purchase  Agreements"),  and such  registration
         shall be effective,  to the extent  requisite to permit the disposition
         of such shares of Common Stock in accordance with the intended  methods
         of disposition thereof referred to in said section 10.5;
 
provided  that  the  requirements  of the  foregoing  clause  (b)  shall  not be
applicable if on the date fixed for such  redemption  such  disposition  of such
shares of Common Stock may be made by the holders of such $.70  Preferred  Stock
without  registration  pursuant  to  section  10.4(i)  or  section  10.10 of the
Purchase  Agreements.  As used in the foregoing clause (b), the term "Securities
Act"  shall  have  the  meaning  specified  in  section  10.2  of  the  Purchase
Agreements.
 
         4.3.  Additional  Redemptions.   Notwithstanding  any  other  provision
hereof,  if Section 302(b)(2) of the Internal Revenue Code as in effect on April
15,  1978 (or any  similar  provision  of the tax laws of the  United  States of
America in effect thereafter) shall not be applicable to any redemption required
by section 4.1 or to any  redemption  proposed to be made under section 4.2, the
corporation  shall,  at the time of such  redemption,  concurrently  redeem such
additional number of shares of the $.70 Preferred Stock as shall, in the opinion
of the firm of independent public accountants  referred to below, be required so
that said Section  302(b)(2) (or such similar  provision) shall be applicable to
such  redemption.  The  corporation  shall  furnish  to each  holder of the $.70
Preferred  Stock,  at least 30 days prior to the date  fixed for any  redemption
under  section 4.1 or section  4.2, a  certificate  of its  principal  financial
officer  certifying that said Section 302(b)(2) (or such similar provision) will
be  applicable  to  such  redemption  and  showing  in  reasonable   detail  all
computations  required  to  demonstrate  such  applicability,  together  with  a
certificate of a firm of independent public  accountants of recognized  national
standing selected by the corporation certifying to such applicability.
<PAGE>
 
         4.4.  Notice  of  Optional  Redemptions.  In the case of each  optional
redemption under section 4.2 hereof,  the corporation  shall give written notice
thereof  to each  holder of the $.70  Preferred  Stock not less than 30 nor more
than 60  days  prior  to the  date  fixed  for  such  redemption,  in each  case
specifying such date, the aggregate number of shares of the $.70 Preferred Stock
to be  redeemed  on such date and the number of shares of $.70  Preferred  Stock
held by such holder to be redeemed on such date.  Such notice  shall be given by
delivering or mailing the same to each such holder at the address of such holder
as it appears on the corporation's stock records.
 
         4.5.  Allocation  of  Partial  Redemptions.  If  less  than  all of the
outstanding  shares of the $.70 Preferred  Stock are to be redeemed  pursuant to
sections 4.1, 4.2 or 4.3 hereof,  the shares of the $.70  Preferred  Stock to be
redeemed shall be allocated in whole shares among all of the holders  ratably in
proportion,  as nearly as practicable,  to the respective numbers of shares held
by such holders, with adjustments,  to the extent practicable, to compensate for
any prior redemptions not allocated exactly in such proportion.
 
         4.6.  Effect of  Redemption.  Upon the date fixed for any redemption of
the $.70  Preferred  Stock,  and upon payment by the  corporation of the amounts
payable on redemption as provided herein, all shares of the $.70 Preferred Stock
redeemed shall be deemed to be no longer outstanding for any purpose, whether or
not  the   certificates   for  such  shares  shall  have  been  surrendered  for
cancellation,  and all rights with respect to such shares shall thereupon cease,
except  only the right of the  holders  of such  shares to receive  the  amounts
payable upon the  redemption  thereof.  All shares of the $.70  Preferred  Stock
redeemed  by the  corporation  shall be retired and  cancelled  and shall not be
reissued.
 
5.       Conversion.
 
         5.1. Conversion Privilege.  Any shares of the $.70 Preferred Stock may,
at the  election  of the  holder  thereof,  at any time  prior  to the  close of
business  on May 31, 1993 be  converted,  at the  conversion  price per share of
Common  Stock  of  $8.50,  as  adjusted  and  readjusted  from  time  to time in
accordance  with section 5.4 hereof (such  conversion  price, as so adjusted and
readjusted  and in effect at any  time,  being  herein  called  the  "Conversion
Price"), into the number of fully paid and non assessable shares of Common Stock
determined  by dividing  (a) the  aggregate  par value of the shares of the $.70
Preferred  Stock to be so  converted,  multiplied  by 10, by (b) the  Conversion
Price in effect at the time of such conversion.
 
         5.2. Manner of Conversion, etc. The certificate or certificates for any
shares of the $.70 Preferred  Stock to be converted  shall be surrendered at the
office or agency  maintained  for such  purpose  pursuant to section 5.9 hereof,
duly  endorsed,  or  accompanied  by  proper  instruments  of  transfer,  to the
corporation or in blank, and accompanied by written notice to the corporation of
the holder's  election to make such conversion and of the name or names in which
the certificate or certificates for shares of Common Stock are to be issued. The
right to convert any shares of the $.70  Preferred  Stock called for  redemption
shall  terminate  at the close of  business on the last full  business  day next
preceding the date fixed for such  redemption.  Upon conversion of any shares of
the $.70 Preferred Stock, the corporation  shall pay to the holder thereof a sum
equal to Full  Cumulative  Dividends  thereon  to the date of  conversion.  Each
conversion  shall be deemed to have been effected as of the close of business on
the  date  on  which  such  certificate  or  certificates  shall  have  been  so
 
<PAGE>
 
surrendered  to such  agency,  and at such time the rights of the holder of $.70
Preferred  Stock as such  shall,  to the extent of the number of shares  thereof
converted,  cease,  and the  person  or  persons  in  whose  name or  names  any
certificate  or  certificates  for shares of Common Stock shall be issuable upon
such  conversion  shall be deemed to have become the holder or holders of record
thereof.
 
         5.3. Delivery of Stock Certificates;  Fractional Shares. As promptly as
practicable  after the conversion of any $.70 Preferred  Stock, and in any event
within 20 days thereafter, the corporation at its expense (including the payment
by it of any  applicable  issue  taxes)  will issue and deliver to the holder of
such $.70 Preferred Stock, or as such holder (upon payment by such holder of any
applicable  transfer taxes) may direct,  a certificate or  certificates  for the
number of full shares of Common Stock  issuable upon such  conversion,  plus, in
lieu of any fractional  share to which such holder would  otherwise be entitled,
cash equal to such fraction  multiplied by the then current  Market Price of one
full  share,  determined  as  provided in clause  (viii) of  subdivision  (b) of
section 5.4 hereof.
 
         5.4. Adjustment of Conversion Price for Diluting Issues, Distributions.
 
                  (a) Adjustment for Sales Below Conversion  Price,  etc. If and
whenever after April 15, 1978 the corporation  shall issue or sell any shares of
its Common Stock for a consideration per share less than the Conversion Price in
effect  immediately  prior  to the  time of  such  issue  or  sale,  and/or  the
corporation  shall  issue or sell any  shares of its  Common  Stock  (except  on
conversion of $.70 Preferred Stock) for a consideration  per share less than the
Market Price on the date of such issue or sale, then,  forthwith upon such issue
or sale,  the  Conversion  Price  shall be  reduced  to the lower of the  prices
(calculated to the nearest cent) determined as follows:
 
                           (i) by dividing (A) an amount equal to the sum of (1)
                  the number of shares of Common Stock  outstanding  immediately
                  prior to such issue or sale  multiplied  by the then  existing
                  Conversion Price, and (2) the consideration,  if any, received
                  by the  corporation  upon such issue or sale, by (B) the total
                  number of shares of Common Stock outstanding immediately after
                  such issue or sale; and
 
                           (ii) by multiplying  the  Conversion  Price in effect
                  immediately  prior  to the  time  of such  issue  or sale by a
                  fraction,  the  numerator of which shall be the sum of (A) the
                  number of shares of Common Stock outstanding immediately prior
                  to  such  issue  or  sale   multiplied  by  the  Market  Price
                  immediately   prior  to  such  issue  or  sale  plus  (B)  the
                  consideration  received by the corporation  upon such issue or
                  sale, and the denominator of which shall be the product of (C)
                  the  total  number  of  shares  of  Common  Stock  outstanding
                  immediately  after such issue or sale,  multiplied  by (D) the
                  Market Price immediately prior to such issue or sale.
 
                  (b) For the purposes of subdivision  (a) above,  the following
clauses (i) to (x), inclusive, shall also be applicable:
 
 
<PAGE>
 
                           (i)  Issuance  of Rights or  Options.  In case at any
                  time the  corporation  shall  grant  (whether  directly  or by
                  assumption in a merger or  otherwise)  any rights to subscribe
                  for or to purchase, or any options for the purchase of, Common
                  Stock  or  any  stock  or  securities   convertible   into  or
                  exchangeable   for   Common   Stock   (such   convertible   or
                  exchangeable   stock  or   securities   being  herein   called
                  "Convertible  Securities")  whether  or  not  such  rights  or
                  options  or  the  right  to  convert  or  exchange   any  such
                  Convertible  Securities are immediately  exercisable,  and the
                  price per share for which  Common  Stock is issuable  upon the
                  exercise  of such  rights or  options  or upon  conversion  or
                  exchange  of  such  Convertible   Securities   (determined  by
                  dividing (A) the total amount,  if any, received or receivable
                  by the corporation as  consideration  for the granting of such
                  rights  or  options,  plus the  minimum  aggregate  amount  of
                  additional  consideration  payable to the corporation upon the
                  exercise of all such rights or options,  plus,  in the case of
                  such rights or options which relate to Convertible Securities,
                  the minimum aggregate amount of additional  consideration,  if
                  any,  payable  upon  the  issue  or sale  of such  Convertible
                  Securities and upon the conversion or exchange thereof, by (B)
                  the total  maximum  number of shares of Common Stock  issuable
                  upon  the  exercise  of such  rights  or  options  or upon the
                  conversion  or  exchange  of all such  Convertible  Securities
                  issuable upon the exercise of such rights or options) shall be
                  less than the Conversion Price in effect  immediately prior to
                  the time of the  granting  of such  rights or options (or less
                  than the Market  Price,  determined as of the date of granting
                  such  rights or options,  as the case may be),  then the total
                  maximum  number of shares of Common  Stock  issuable  upon the
                  exercise  of such  rights or  options  or upon  conversion  or
                  exchange  of the  total  maximum  amount  of such  Convertible
                  Securities  issuable  upon  the  exercise  of such  rights  or
                  options  shall (as of the date of  granting  of such rights or
                  options) be deemed to be  outstanding  and to have been issued
                  for such price per share.  Except as provided in clause  (iii)
                  below, no further adjustments of the Conversion Price shall be
                  made upon the  actual  issue of such  Common  Stock or of such
                  Convertible Securities upon exercise of such rights or options
                  or upon the actual issue of such Common Stock upon  conversion
                  or exchange of such Convertible Securities.
 
                           (ii) Issuance of Convertible Securities.  In case the
                  corporation  shall issue (whether directly or by assumption in
                  a merger or  otherwise)  or sell any  Convertible  Securities,
                  whether or not the rights to  exchange  or convert  thereunder
                  are immediately exercisable, and the price per share for which
                  Common  Stock is  issuable  upon such  conversion  or exchange
                  (determined  by  dividing  (A) the total  amount  received  or
                  receivable by the corporation as  consideration  for the issue
                  or sale of  such  Convertible  Securities,  plus  the  minimum
                  aggregate amount of additional consideration,  if any, payable
                  to the corporation upon the conversion or exchange thereof, by
                  (B) the  total  maximum  number  of  shares  of  Common  Stock
                  issuable   upon  the   conversion  or  exchange  of  all  such
                  Convertible  Securities)  shall be less  than  the  Conversion
                  Price in effect immediately prior to the time of such issue or
 
<PAGE>
 
                  sale (or less than the Market Price, determined as of the date
                  of such issue or sale of such Convertible  Securities,  as the
                  case may be),  then the  total  maximum  number  of  shares of
                  Common Stock issuable upon  conversion or exchange of all such
                  Convertible  Securities  shall (as of the date of the issue or
                  sale  of  such   Convertible   Securities)  be  deemed  to  be
                  outstanding  and to have been issued for such price per share,
                  provided that (1) except as provided in clause (iii) below, no
                  further adjustments of the Conversion Price shall be made upon
                  the  actual  issue of such  Common  Stock upon  conversion  or
                  exchange of such Convertible  Securities,  and (2) if any such
                  issue  or sale of such  Convertible  Securities  is made  upon
                  exercise of any rights to subscribe  for or to purchase or any
                  option to purchase any such  Convertible  Securities for which
                  adjustments  of the  Conversion  Price  have been or are to be
                  made pursuant to other  provisions of this subdivision (b), no
                  further  adjustment of the  Conversion  Price shall be made by
                  reason of such issue or date.
 
                           (iii) Change in Option Price or Conversion Rate. Upon
                  the happening of any of the following  events,  namely, if the
                  purchase price provided for in any rights or options  referred
                  to in  clause  (i) of this  subdivision  (b),  the  additional
                  consideration, if any, payable upon the conversion or exchange
                  of Convertible  Securities referred to in clause (i) or clause
                  (ii)  of this  subdivision  (b),  or the  rate  at  which  any
                  Convertible  Securities  referred  to in clause  (i) or clause
                  (ii)  of  this   subdivision  (b)  are  convertible   into  or
                  exchangeable  for Common Stock shall change  (other than under
                  or  by  reason  of  provisions  designed  to  protect  against
                  dilution),  the Conversion Price in effect at the time of such
                  event shall  forthwith be readjusted to the  Conversion  Price
                  which would have been in effect at such time had such  rights,
                  options or Convertible  Securities still outstanding  provided
                  for such changed purchase price,  additional  consideration or
                  conversion  rate,  as the case may be,  at the time  initially
                  granted,  issued or sold;  and on the  expiration  of any such
                  option  or  right  or the  termination  of any  such  right to
                  convert  or  exchange   such   Convertible   Securities,   the
                  Conversion  Price then in effect  hereunder shall forthwith be
                  increased  to the  Conversion  Price  which would have been in
                  effect at the time of such  expiration or termination had such
                  right,   option  or  Convertible   Security,   to  the  extent
                  outstanding   immediately   prior   to  such   expiration   or
                  termination,  never been issued, and the Common Stock issuable
                  thereunder shall no longer be deemed to be outstanding. If the
                  purchase  price  provided  for in any  such  right  or  option
                  referred to in clause (i) of this  subdivision (b) or the rate
                  at which any Convertible  Securities referred to in clause (i)
                  or clause (ii) of this subdivision (b) are convertible into or
                  exchangeable  for Common  Stock,  shall  decrease  at any time
                  under or by reason of provisions with respect thereto designed
                  to protect against  dilution,  then in case of the delivery of
                  Common  Stock upon the exercise of any such right or option or
                  upon conversion or exchange of any such Convertible  Security,
                  the Conversion  Price then in effect hereunder shall forthwith
                  be adjusted to such  respective  amount as would have obtained
 
<PAGE>
 
                  had such  right,  option or  Convertible  Security  never been
                  issued as to such Common Stock and had  adjustments  been made
                  upon the issuance of the shares of Common  Stock  delivered as
                  aforesaid,  but only if as a  result  of such  adjustment  the
                  Conversion   Price  then  in  effect   hereunder   is  thereby
                  decreased.
 
                           (iv) Stock Dividends.  In case the corporation  shall
                  declare a dividend  or snake any other  distribution  upon any
                  stock  of  the   corporation   payable  in  Common   Stock  or
                  Convertible  Securities,   any  Common  Stock  or  Convertible
                  Securities,  as the case may be,  issuable  in payment of such
                  dividend or  distribution  shall be deemed to have been issued
                  or sold without consideration.
 
                           (v)  Consideration  for Stock.  In case any shares of
                  Common  Stock  or  Convertible  Securities  or any  rights  or
                  options  to  purchase  any such  Common  Stock or  Convertible
                  Securities shall be issued or sold for cash the  consideration
                  received therefor shall be deemed to be the amount received by
                  the corporation  therefor,  without deduction therefrom of any
                  expenses   incurred  or  any   underwriting   commissions   or
                  concessions  paid or allowed by the  corporation in connection
                  therewith.  In case any shares of Common Stock or  Convertible
                  Securities  or any  rights or  options  to  purchase  any such
                  Common Stock or Convertible Securities shall be issued or sold
                  for a  consideration  other  than  cash,  the  amount  of  the
                  consideration  other  than cash  received  by the  corporation
                  shall be deemed to be the fair value of such  consideration as
                  determined  in good  faith by the  Board of  Directors  of the
                  Corporation, without deduction of any expenses incurred or any
                  underwriting commissions or concessions paid or allowed by the
                  corporation  in  connection  therewith.  In case any shares of
                  Common  Stock  or  Convertible  Securities  or any  rights  or
                  options  to  purchase   such  Common   Stock  or   Convertible
                  Securities  shall be issued in  connection  with any merger or
                  consolidation  in  which  the  corporation  is  the  surviving
                  corporation,  the amount of  consideration  therefor  shall be
                  deemed  to be the fair  value as  determined  by the  Board of
                  Directors of the corporation of such portion of the assets and
                  business of the  non-surviving  corporation or corporations as
                  such Board shall  determine to be  attributable to such Common
                  Stock, Convertible Securities,  rights or options, as the case
                  may be.  In the  event of any  consolidation  or merger of the
                  corporation  in which  the  corporation  is not the  surviving
                  corporation   or  in  the   event   of  any  sale  of  all  or
                  substantially  all of the assets of the  corporation for stock
                  or other securities of any corporation,  the corporation shall
                  be  deemed to have  issued a number  of  shares of its  Common
                  Stock  for  stock  or  securities  of  the  other  corporation
                  computed  on the basis of the actual  exchange  ratio on which
                  the transaction  was predicated and for a consideration  equal
                  to the fair market  value on the date of such  transaction  of
                  such stock or securities of the other corporation.
<PAGE>
 
                           (vi) Record Date. In case the corporation  shall take
                  a record of the holders of its Common Stock for the purpose of
                  entitling them (A) to receive a dividend or other distribution
                  payable in Common Stock or in Convertible  Securities,  or (B)
                  to  subscribe  for or  purchase  Common  Stock or  Convertible
                  Securities,  then such  record  date shall be deemed to be the
                  date of the issue or sale of the shares of Common Stock deemed
                  to have been issued upon the  declaration  of such dividend or
                  the  making  of such  other  distribution  or the  date of the
                  granting of such right of  subscription  or  purchase,  as the
                  case may be.
 
                           (vii) Treasury Shares. The number of shares of Common
                  Stock  outstanding  at any given time shall not include shares
                  owned or held by or for the  account of the  corporation,  and
                  the  disposition  of any such shares  shall be  considered  an
                  issue  or sale  of  Common  Stock  for  the  purposes  of this
                  subdivision (b).
 
                           (viii)  Definition  of Market Price.  "Market  Price"
                  shall mean in the case of any  trading  day the average of the
                  closing  prices of the Common Stock sales on all  exchanges on
                  which the Common Stock may at the time be listed, or, if there
                  shall have been no sales on any such exchange on any such day,
                  the  average  of the bid and  asked  prices at the end of such
                  day,  or, if the  Common  Stock  shall not be so  listed,  the
                  average of the bid and asked  prices at the end of such day in
                  the over-the-counter market, in each such case (except for the
                  purposes of section 4.2 hereof)  averaged  over a period of 20
                  consecutive business days prior to the day as of which "market
                  price" is being determined. If at any time the Common Stock is
                  not listed on any  exchange or quoted in the  over-the-counter
                  market, the "Market Price" shall be deemed to be the higher of
                  (A) the  book  value  thereof  as  determined  by any  firm of
                  independent public accountants of recognized national standing
                  selected by the Board of  Directors of the  corporation  as at
                  the last day of any month ending within 60 days  preceding the
                  date as of which  the  determination  is to be made or (B) the
                  fair value  thereof  determined  in good faith by the Board of
                  Directors of the  corporation  as of a date which is within 15
                  days of the date as of which the determination is to be made.
 
                           (ix)  Determination  of Market  Price  under  Certain
                  Circumstances.     Anything    herein    to    the    contrary
                  notwithstanding,  in case  the  corporation  shall  issue  any
                  shares of Common Stock or Convertible Securities in connection
                  with the acquisition by the corporation of the stock or assets
                  of  any  other   corporation   or  the  merger  of  any  other
                  corporation into the corporation under  circumstances where on
                  the date of the  issuance  of such  shares of Common  Stock or
                  Convertible  Securities  the  consideration  received for such
                  Common  Stock or deemed to have been  received  for the Common
                  Stock into which such  Convertible  Securities are convertible
                  is less than the Market Price of the Common Stock,  but on the
                  date the  number  of shares  of  Common  Stock or  Convertible
                  Securities  (or in the case of  Convertible  Securities  other
 
<PAGE>
 
                  than stock,  the  aggregate  principal  amount of  Convertible
                  Securities) was determined the consideration received for such
                  Common  Stock or deemed to have been  received  for the Common
                  Stock into which such  Convertible  Securities are convertible
                  would not have been less than the Market Price  thereof,  such
                  shares of Common Stock shall not be deemed to have been issued
                  for less than the Market Price of the Common Stock.
 
                           (x) Determination of Consideration in Connection with
                  Certain   Acquisitions.   Anything   in  clause  (v)  of  this
                  subdivision (b) to the contrary  notwithstanding,  in the case
                  of an  acquisition  where all or part of the purchase price is
                  payable  in  Common  Stock or  Convertible  Securities  but is
                  stated as a dollar amount,  where the corporation  upon making
                  the  acquisition  pays only part of a maximum dollar  purchase
                  price  which  is  payable  in  Common  Stock  or   Convertible
                  Securities  and where the  balance of such  purchase  price is
                  deferred or is contingently payable under a formula related to
                  earnings over a period of time, (A) the consideration received
                  for any Common Stock or  Convertible  Securities  delivered at
                  the time of the acquisition shall be deemed to be such part of
                  the total  consideration as the portion of the dollar purchase
                  price  then paid in  Common  Stock or  Convertible  Securities
                  bears to the total maximum  dollar  purchase  price payable in
                  Common Stock or Convertible Securities,  and (B) in connection
                  with each issuance of additional  Common Stock or  Convertible
                  Securities  pursuant to the terms of the agreement relating to
                  such acquisition,  the consideration  received shall be deemed
                  to be such part of the total  consideration  as the portion of
                  the dollar purchase price then and theretofore  paid in Common
                  Stock or  Convertible  Securities  bears to the total  maximum
                  dollar  purchase  price payable in Common Stock or Convertible
                  Securities  multiplied  by a fraction,  the numerator of which
                  shall be the number of shares  (or in the case of  Convertible
                  Securities other than stock, the aggregate  principal  amount)
                  then  issued and the  denominator  of which shall be the total
                  number of  shares  (or in the case of  Convertible  Securities
                  other than stock,  the  aggregate  principal  amount) then and
                  theretofore issued under such acquisition agreement.  If it is
                  determined that any part of the deferred or contingent portion
                  of such purchase  price shall not be payable,  the  Conversion
                  Price then in effect  hereunder  shall forthwith be readjusted
                  to such  Conversion  Price as would have  obtained (l) had the
                  adjustment made in connection with such  acquisition been made
                  upon the basis of the issuance of only the number of shares of
                  Common  Stock or  Convertible  Securities  actually  issued in
                  connection with such acquisition, and (2) had adjustments been
                  made on the  basis  of the  Conversion  Price as  adjusted  in
                  clause (1) for all issues or sales (as prices which would have
                  affected  such adjusted  Conversion  Price) of Common Stock or
                  rights,  options  or  Convertible  Securities  made after such
                  acquisition.  In the event  that  only a part of the  purchase
                  price  for  an   acquisition   is  paid  in  Common  Stock  or
                  Convertible  Securities  in the  manner  referred  to in  this
                  clause  (x),  the term "total  consideration"  as used in this
 
<PAGE>
 
                  clause (x) shall mean that part of the aggregate consideration
                  as is fairly  allocable to the  purchase  price paid in Common
                  Stock or Convertible  Securities in the manner  referred to in
                  this clause (x), as  determined  by the Board of  Directors of
                  the corporation.
 
                  (c)  Adjustment  for Certain  Special  Dividends.  In case the
corporation  shall declare a dividend  upon the Common Stock  payable  otherwise
than out of consolidated earnings or consolidated earned surplus,  determined in
accordance with generally accepted accounting  principles,  including the making
of appropriate deductions for minority interests,  if any, in Subsidiaries,  and
otherwise than in Common Stock or Convertible  Securities,  the Conversion Price
in effect immediately prior to the declaration of such dividend shall be reduced
by an amount  equal,  in the case of a dividend in cash,  to the amount  thereof
payable per share of the Common Stock or, in the case of any other dividend,  to
the fair value  thereof per share of the Common Stock as determined by the Board
of Directors of the  corporation.  For the purposes of the  foregoing a dividend
other than in cash shall be considered payable out of earnings or surplus (other
than  revaluation  or paid-in  surplus) only to the extent that such earnings or
surplus  are  charged  an amount  equal to the fair  value of such  dividend  as
determined by the Board of Directors of the  corporation.  Such reductions shall
take  effect as of the date on which a record is taken for the  purpose  of such
dividend,  or, if a record is not  taken  the date as of which  the  holders  of
Common Stock of record entitled to such dividend are to be determined.
 
                  (d)   Subdivision  or  Combination  of  Stock.   In  case  the
corporation  shall at any time subdivide its outstanding  shares of Common Stock
into a greater  number of shares,  the  Conversion  Price in effect  immediately
prior to such subdivision shall be proportionately  reduced, and conversely,  in
case the outstanding shares of Common Stock of the corporation shall be combined
into a smaller  number of shares,  the  Conversion  Price in effect  immediately
prior to such Combination shall be proportionately increased.
 
                  (e) Reorganization, Reclassification, Consolidation, Merger or
Sale. If any capital  reorganization or reclassification of the capital stock of
the  corporation,  or  consolidation  or merger of the corporation  with another
corporation,  or the sale of all or  substantially  all of its assets to another
corporation  shall be effected in such a way that  holders of Common Stock shall
be  entitled  to  receive  stock,  securities  or assets  with  respect to or in
exchange  for  Common  Stock,  then,  as a  condition  of  such  reorganization,
reclassification,  consolidation,  merger or sale, lawful and adequate provision
shall be made whereby each holder of $.70 Preferred Stock shall  thereafter have
the  right to  purchase  and  receive  upon the  basis  and upon the  terms  and
conditions specified herein and in lieu of the shares of the Common Stock of the
corporation  immediately  theretofore  issuable upon the conversion of such $.70
Preferred Stock, such shares of stock, securities, or assets as may be issued or
payable  with respect to or in exchange  for a number of  outstanding  shares of
such  Common  Stock  equal to the  number of shares  of such  stock  immediately
theretofore  issuable upon the conversion of such $.70 Preferred  Stock had such
reorganization, reclassification, consolidation, merger or sale not taken place,
and in any such case  appropriate  provision  shall be made with  respect to the
rights and interests of the holders of the $.70 Preferred  Stock to the end that
the provisions hereof (including without  limitation  provisions for adjustments
of the Conversion Price) shall thereafter be applicable, as nearly as may be, in
relation to any shares of stock,  securities,  or assets thereafter  deliverable
upon the  conversion of the $.70  Preferred  Stock.  The  corporation  shall not
 
<PAGE>
 
effect any such  consolidation,  merger or sale,  unless  prior to  consummation
thereof the successor corporation (if other than the corporation) resulting from
such  consolidation or merger,  or the corporation into or for the securities of
which the  outstanding  shares of Common  Stock shall be changed or exchanged in
connection with such consolidation or merger or the corporation  purchasing such
assets shall assume by written instrument  executed and mailed to each holder of
$.70 Preferred Stock at the time outstanding,  the obligation to deliver to such
holder such shares of stock,  securities  or assets as, in  accordance  with the
foregoing provisions,  such holder may be entitled to. If a purchase,  tender or
exchange  offer is made to and  accepted  by the holders of more than 50% of the
outstanding shares of Common Stock of the corporation, the corporation shall not
effect  any  consolidation,  a merger or sale with the person  having  made such
offer,  unless  prior  to the  consummation  thereof  the  holders  of the  $.70
Preferred Stock shall have been given a reasonable  opportunity to then elect to
receive  upon the  conversion  of the $.70  Preferred  Stock  either  the stock,
securities  or assets  then  issuable  with  respect to the Common  Stock of the
corporation or the stock,  securities or assets,  or the  equivalent,  issued to
previous holders of the Common Stock in accordance with such offer.
 
                  (f)  Notice  of   Adjustment.   Upon  any  adjustment  of  the
Conversion  Price, then and in each such case the corporation shall give written
notice thereof to each holder of $.70 Preferred  Stock at the time  outstanding,
which notice shall state the Conversion  Price  resulting from such  adjustment,
and shall set forth in reasonable  detail the method of calculation  thereof and
the facts upon which such  calculation  is based.  Such notice shall be given by
delivering or mailing the same to each such holder at the address of such holder
as it appears on the corporation's stock records.
 
                  (g)      Other Notices.  In case at any time:
 
                           (i) the  corporation  shall declare any such dividend
                  on its  Common  Stock at a rate in  excess  of the rate of the
                  last cash dividend theretofore paid;
 
                           (ii) the corporation  shall pay any dividend  payable
                  in stock upon its Common Stock or make any distribution (other
                  than  regular  cash  dividends)  to the  holders of its Common
                  Stock;
 
                           (iii) the  corporation  shall offer for  subscription
                  pro rata to the  holders  of its Common  Stock any  additional
                  shares of stock of any class or other rights;
 
                           (iv) there  shall be any capital  reorganization,  or
                  reclassification  of the capital stock of the corporation,  or
                  consolidation  or merger of the  corporation  with, or sale of
                  all  or   substantially   all  of  its  assets   to,   another
                  corporation; or
 
                           (v) there  shall  be  a   voluntary   or  involuntary
                  dissolution,  liquidation or winding up of the corporation;
<PAGE>
 
then,  in any one or more of said  cases,  the  corporation  shall give  written
notice to each holder of $.70 Preferred  Stock at the time  outstanding,  of the
date on which (A) the books of the corporation  shall close or a record shall be
taken  for such  dividend,  distribution  or  subscription  rights,  or (B) such
reorganization,  reclassification,  consolidation,  merger,  sale,  dissolution,
liquidation  or winding up shall take  place,  as the case may be.  Such  notice
shall also  specify the date as of which the  holders of Common  Stock of record
shall  participate in such dividend,  distribution  or subscription  rights,  or
shall be  entitled  to  exchange  their  Common  Stock for  securities  or other
property deliverable upon such reorganization, reclassification,  consolidation,
merger, sale,  dissolution,  liquidation or winding up, as the case may be. Such
notice shall be given by  delivering  or mailing the same to each such holder at
the address of such holder as it appears on the corporation's  stock records, at
least 20 days prior to the action in question and not less than 20 days prior to
the record date or the date on which the corporation's transfer books are closed
in respect thereto.
 
                  (h)  Certain  Events.  If any event  occurs as to which in the
opinion of the Board of Directors of the  corporation  the other  provisions  of
this section 5.4 are not strictly applicable or if strictly applicable would not
fairly protect the conversion  rights of the holders of the $.70 Preferred Stock
in accordance with the essential intent and principles of such provisions,  then
the Board of  Directors  shall make an  adjustment  in the  application  of such
provisions,  in accordance with such essential  intent and principles,  so as to
protect such conversion rights as aforesaid.
 
         5.5.  Shares to be Fully Paid;  Reservation of Shares.  The corporation
covenants and agrees that all shares which may be issued upon  conversion of the
$.70 Preferred Stock will, upon issuance,  be fully paid and  non-assessable and
free from all taxes,  liens and charges with respect to the issue  thereof;  and
without limiting the generality of the foregoing,  the corporation covenants and
agrees that it will from time to time take all such  action as may be  requisite
to assure that the par value per share of the Common Stock is at all times equal
to or less than the then effective  purchase price per share of the Common Stock
issuable upon conversion of the $.70 Preferred  Stock.  The corporation  further
covenants and agrees that the corporation will at all times have authorized, and
reserved for the purpose of issue or transfer  upon the  conversion  of the $.70
Preferred  Stock,  a sufficient  number of shares of its Common Stock to provide
for the conversion of the $.70 Preferred Stock.
 
         5.6. Registration,  Approval and Listing. If any shares of Common Stock
required to be reserved  for  purposes of  conversion  of $.70  Preferred  Stock
hereunder require  registration  with or approval of any governmental  authority
under any Federal or State law, or listing on any national securities  exchange,
before such shares may be issued upon conversion,  the corporation  will, at its
expense, as expeditiously as possible, use its best efforts to cause such shares
to be duly registered or approved or listed on the relevant national  securities
exchange, as the case may be.
 
         5.7. Issue Tax. The issuance of certificates for shares of Common Stock
upon the conversion of $.70 Preferred  Stock shall be made without charge to the
holders of such $.70  Preferred  Stock for any issuance tax in respect  thereof,
provided that the corporation  shall not be required to pay any tax which may be
payable in respect of any transfer  involved in the issuance and delivery of any
certificate  in a name  other  than  the  holder  of the  $.70  Preferred  Stock
converted.
<PAGE>
 
         5.8.  Closing  of  Books.  The  corporation  will at no time  close its
transfer  books  against the  transfer of any shares of Common  Stock  issued or
issuable  upon the  conversion of the $.70  Preferred  Stock in any manner which
interferes with the timely  exercise of the conversion  rights of the holders of
the $.70 Preferred Stock.
 
         5.9.  Conversion  Agent.  So  long  as  any  $.70  Preferred  Stock  is
outstanding,  the corporation  will at all times maintain an office or agency in
Boston,  Massachusetts,  for the  purpose  of  accepting  $.70  Preferred  Stock
surrendered  for  conversion and issuing Common Stock upon the conversion of the
$.70  Preferred  Stock  pursuant to section 5.2 hereof.  Initially the office or
agency  hereunder for such purposes  shall be the principal  office of The First
National Bank of Boston. The corporation will give written notice to each holder
of the $.70 Preferred Stock at the time outstanding of any change in such office
or agency.
 
6.       Voting Rights; Restrictions on Corporate Action.
 
         6.1. General Voting Rights.  Except as otherwise provided by law and in
addition to the rights  provided for in section 6.2 and section 6.3 hereof,  the
holders of the $.70 Preferred Stock shall be entitled to one-tenth (1/10) of one
vote for each share held and shall be entitled to  exercise  such voting  rights
voting with the holders of Common Stock,  without distinction as to class at any
annual or special meeting of  stockholders  for the election of directors and on
any other matter coming before such meeting.
 
         6.2.  Special  Right  to Elect  Director.  (a) If and  whenever  (i) if
dividends on the $.70 Preferred Stock shall have been in arrears for a period of
12 calendar months (whether or not  consecutive),  or (ii) the corporation shall
have  failed to make any  redemption  of the $.70  Preferred  Stock  required by
section 4.1 hereof when due, and such failure or failures  shall have  continued
for a period of 12 calendar months (whether or not consecutive),  the holders of
the  outstanding  $.70  Preferred  Stock  shall have the special  right,  voting
separately as a single class,  to elect one director of the  corporation  at the
next  succeeding  annual meeting of stockholders  and at each succeeding  annual
meeting  of  stockholders   thereafter  until  such  right  shall  terminate  as
hereinafter  provided.  At each meeting of  stockholders at which the holders of
the $.70 Preferred Stock shall have such special right,  voting  separately as a
single  class,  to elect a director,  the  presence in person or by proxy of the
holders  of  record  of  one-third  of the  total  number  of shares of the $.70
Preferred  Stock at the time  outstanding  shall be necessary and  sufficient to
constitute a quorum of such class for such  election by such  stockholders  as a
class.
<PAGE>
 
                  (b) Each director elected by the holders of the $.70 Preferred
Stock voting separately as a single class as provided in subdivision (a) of this
section  6.2 shall hold office  until the annual  meeting of  stockholders  next
succeeding  his  election  and until his  successor,  if any, is elected by such
holders and qualified or until his death,  resignation  or removal in the manner
provided in the by-laws of the  corporation.  In case the office of any director
shall become vacant, such vacancy may be filled for the unexpired portion of the
term  by the  vote of such  stockholders  given  at a  special  meeting  of such
stockholders called for the purpose.
 
                  (c) Whenever Full  Cumulative  Dividends on the $.70 Preferred
Stock for all past  Dividend  Periods and for the then current  Dividend  Period
shall have been declared and paid,  and all  redemptions  of the $.70  Preferred
Stock  required  by section  4.1 hereof  shall have been made,  the right of the
holders of the $.70 Preferred  Stock,  voting  separately as a single class,  to
elect a director  as  provided  in  subdivision  (a) of this  section  6.2 shall
terminate at the next  succeeding  annual meeting of  stockholders,  but subject
always to the same  provisions  for the vesting of such  special  right,  voting
separately as a single class, to elect a director in the case of any future such
arrearage or failure.
 
         6.3.  Restrictions  on  Corporate  Action.  Without  the consent of the
holders of at least a majority of the shares of the $.70 Preferred  Stock at the
time  outstanding,  given in  writing  without a meeting or by vote at a meeting
called for the purpose,  at which the holders of the $.70 Preferred  Stock shall
vote separately as a single class, the corporation shall not
 
                  (a)  Authorize  or issue any  shares  of  Senior  Stock or any
shares of stock or any  obligations  or warrants or rights  convertible  into or
evidencing rights to purchase any Senior Stock;
 
                  (b)  Authorize  or issue any  shares  of  Parity  Stock or any
shares of stock or any  obligations  or warrants or rights  convertible  into or
evidencing rights to purchase any Parity Stock unless,  immediately after giving
effect  thereto and to any  concurrent  transactions,  Consolidated  Net Income.
Available  for  Dividends  for the  period of the four most  recently  completed
quarterly  accounting  periods of the  corporation  shall have equalled at least
150% of Pro Forma Interest and Preferred Dividends;
 
                  (c) Declare, order, pay, make or set apart any sum or property
for any Junior Stock  Payment  (except to the extent of the  aggregate  net cash
proceeds received by the corporation after the date of initial issue of the $.70
Preferred  Stock from the sale of shares of Junior Stock or of warrants,  rights
or options to acquire any such shares) unless,  immediately  after giving effect
thereto, Consolidated Net Worth shall be at least $8,000,000;
 
                  (d)  Take  any  action   looking   towards   its  liquidation,
dissolution or winding up;
 
                  (e)  Consolidate  with or merge into any other person,  unless
(i) the holders of the $.70 Preferred  Stock will receive in such  consolidation
or merger the same number of shares of stock of the  corporation  resulting from
or surviving such  consolidation or merger,  having the same relative rights and
preferences  as the $.70 Preferred  Stock,  and (ii) after giving effect to such
consolidation  or merger,  the  corporation  resulting  from or  surviving  such
consolidation or merger will have no stock authorized or outstanding  having any
 
<PAGE>
 
right or  preference as to dividends or assets senior to any right or preference
of the $.70  Preferred  Stock or of the stock  issued to the holders of the $.70
Preferred Stock in such consolidation or merger;
 
                  (f)  Sell,  lease,  abandon  or  otherwise  dispose  of all or
substantially all of its properties and assets, except that the corporation may,
without such consent,  sell or otherwise  dispose of all or substantially all of
its  properties  and assets to another  corporation if as a result of such trans
action (i) the holders of the $.70 Preferred  Stock will  thereupon  receive the
same  number of  shares  of stock of the  corporation  purchasing  or  otherwise
acquiring  such  properties  and  assets,  having the same  relative  rights and
preferences  as the $.70 Preferred  Stock,  and (ii) after giving effect to such
transaction,  the corporation  purchasing or otherwise acquiring such properties
and assets  will have no stock  authorized  or  outstanding  having any right or
preference  as to dividends or assets  senior to any right or  preference of the
$.70 Preferred Stock or of the stock issued to the holders of the $.70 Preferred
Stock in such transaction;
 
                  (g) Enter into any agreement or understanding which in any way
restricts the corporation's right or ability to declare and pay dividends on, or
to make any other distribution with respect to, or to redeem, the $.70 Preferred
Stock; or
 
                  (h)  Authorize or effect any amendment to its  Certificate  of
Incorporation  or by-laws which would adversely  affect or be inconsistent  with
any of the  rights  or  preferences  of the $.70  Preferred  Stock or  otherwise
prejudicial to the interests of the holders of the $.70 Preferred Stock.
 
7.  Change in Tax Laws.  In the event that the tax laws of the United  States of
America are  amended  after  April 15,  1978 so as to allow the  corporation  to
elect, for Federal income tax purposes,  whether or not to claim a deduction for
dividends or other  distributions  on or on account of the $.70 Preferred Stock,
the corporation  shall not, without the unanimous  consent of the holders of the
shares of the $.70  Preferred  Stock at the time  outstanding,  given in writing
without a meeting or by vote at a Meeting  called for the purpose,  at which the
holders of the $.70  Preferred  Stock snail vote  separately  as a single class,
elect to claim  any such  deduction  if as a  result  of such  election  (a) the
deduction  for  dividends  received  provided for in Section 243 of the Internal
Revenue  Code as in effect on April 15, 1978 with  respect to  dividends  on the
$.70  Preferred  Stock  received by any holder  thereof  would be  eliminated or
reduced,  or (b) the interests of the holders of the $.70 Preferred  Stock would
otherwise be adversely affected.
 
8.       Definitions; Accounting Terms and Principles.
 
         8.1.     Definitions   of   Capitalized   Terms.  As  used  herein  the
following  terms  have the  following respective meanings:
 
         Common Stock:  the Common Stock,  $1 par value,  of the  corporation as
constituted  on the date of initial issue of the $.70 Preferred  Stock,  and any
stock  into which  such  Common  Stock  shall  have been  changed,  or any stock
resulting from any subdivision,  Combination,  consolidation or reclassification
of such Common Stock.
 
         Consolidated   Net  Income,   Consolidated  Net  Income  Available  for
Dividends and Consolidated  Net Worth: the Net Income,  Net Income Available for
dividends  and Net  Worth,  as the  case  may  be,  of the  corporation  and its
Subsidiaries (whether or not ordinarily  consolidated in consolidated  financial
 
<PAGE>
 
statements of the corporation and Subsidiaries),  all consolidated in accordance
with generally  accepted  accounting  principles,  and after giving  appropriate
effect to outside minority interests, if any, in Subsidiaries,  provided that in
determining  Consolidated  Net Income there shall be excluded (a) the Net Income
of  any  person  other  than a  Subsidiary)  in  which  the  corporation  or any
Subsidiary  has an  ownership  interest,  except to the extent that any such Net
Income has been actually  received by the  corporation or such Subsidiary in the
form of dividends or similar distributions,  (b) any undistributed Net Income of
a  Subsidiary  which  for any  reason is  unavailable  for  distribution  to the
corporation  or any  other  Subsidiary,  and (c) any  deferred  or other  credit
representing  amortization  of the excess of the equity in any Subsidiary at the
date of acquisition thereof over the cost of the investment in such Subsidiary.
 
         Conversion Price:  as defined in section 5.1 thereof.
 
         Convertible Securities:  as  defined  in  clause (i) of subdivision (b)
of section 5.4 hereof.
 
         Dividend  Periods:  the periods beginning on January 16, April 16, July
l6 and  October 16 and ending on April 15,  July 15,  October 15 and January 15,
respectively, in each year.
 
         Full Cumulative  Dividends:  cumulative dividends on the $.70 Preferred
Stock  computed,  to the date or for the Dividend Period with reference to which
the term is used,  at the rate of $.70 per share per annum  (whether or not such
amount or any part thereof shall have been declared as dividends, whether or not
there exists or shall have  existed  available  funds out of which  dividends in
such amount might be or might  therefore  have been  declared and whether or not
declarations  or payment of dividends in such amount shall be or shall have been
in contravention of any applicable  restrictions from time to time in effect for
the benefit of holders of any class of  indebtedness of the  corporation),  less
the  aggregate  of  dividends  paid  thereon  to such date or for such  Dividend
Period, as the case may be.
 
         Junior Stock:  the Common Stock and any other stock of the  corporation
having rights and  preferences as to dividends and assets junior in all respects
to the rights and preferences of the $.70 Preferred Stock.
 
         Junior Stock  Payment:  any dividend or other  distribution,  direct or
indirect,  on or on account of any shares of any Junior Stock then or thereafter
outstanding, except a dividend payable solely in shares of Junior Stock, and any
redemption,  retirement,  purchase or other acquisition,  direct or indirect, of
any shares of any Junior Stock then or thereafter outstanding or of any warrants
or  rights  to  purchase  any  such  Stock,   except  to  the  extent  that  the
consideration  for any such  redemption,  retirement,  purchase  or  acquisition
consists of shares of Junior Stock.
 
         Market Price:  as  defined  in  clause  (viii)  of  subdivision  (b) of
section 5.4 hereof.
 
         Net Income  of  any   corporation   for any period:  the net income (or
net deficit) of such  corporation  for such period,  determined in the following
manner:
<PAGE>
 
                  (a) the gross revenues and other proper income credits of such
         corporation  shall be  computed  for such  period  in  accordance  with
         generally  accepted  accounting  principles,  excluding,  however,  the
         following items (without duplication):
 
                           (i)      the proceeds of any life insurance policy;
 
                           (ii) gains arising from the sale or other disposition
                  of capital  assets or arising  from any  write-up of assets or
                  from the  acquisition by such  corporation of its  outstanding
                  debt  securities  at a cost which is less than the amounts due
                  and to become due on such securities;
 
                           (iii) any reversal of any contingency reserve, except
                  to the extent  that  provision  for such  contingency  reserve
                  shall have been made during such period; and
 
                           (iv) any reversal of any reserve for taxes,  contract
                  renegotiation or price determination,  except to the extent of
                  any  excess of any such  reserve  over the  amount  ultimately
                  determined  to be due and payable;  but in any event there may
                  be  added  to the  income  credits  for  such  period  (x) the
                  appropriate  portion of any reversal of a reserve  referred to
                  in the foregoing  clauses (iii) and (iv), after allocating the
                  amount of such reversal proportionately over the periods since
                  such reserve was created, and (y) amounts repaid,  refunded or
                  credited to such corporation  during such period on account of
                  taxes paid or accrued in respect of income arising prior to as
                  well as during such period.
 
                  (b) From the amount of such gross  revenues  and other  proper
income  credits  for  such  period,  determined  as  provided  in the  foregoing
subdivision  (a),  there shall be deducted  all  expenses  and all other  proper
revenue  and  income  deductions  and  charges  for such  period  determined  in
accordance with generally accepted  accounting  principles,  exclusive of losses
arising from the sale,  abandonment or other disposition of capital assets,  but
in any event there shall be deducted the  following  items,  whether or not such
items are charged or properly chargeable to income:
 
                           (i)      amortization  of debt discount and any other
                  amortization  of  prepaid  expenses, deferred charges or other
                  intangibles;
 
                           (ii)  provision  for all  taxes  of  every  kind  and
                  character,  provided  that,  for the  purposes  of this clause
                  (ii),  taxes in  respect  of  income  shall  be  appropriately
                  adjusted to reflect the effect of the  exclusion  of any items
                  of  income   credits  and   deductions   (including,   without
                  limitation  any  depreciation,   depletion,   obsolescence  or
                  amortization  claimed  by  such  corporation  for  income  tax
                  purposes  in  excess of the  amount  required  to be  deducted
                  pursuant  to clause (iv) below)  required or  permitted  to be
                  excluded in determining Net Income hereunder;
 
                           (iii) all provisions or appropriations,  if any, made
                  by such corporation for reserves for  contingencies  which are
                  charged or, under generally  accepted  accounting  principles,
                  should be charged to income arising during such period;
<PAGE>
 
                           (iv)   provision   for    depreciation,    depletion,
                  obsolescence  and  amortization  of  the  properties  of  such
                  corporation  (including,  without limitation,  amortization of
                  assets  recorded  under  capital  leases)  in  amounts  in the
                  aggregate not less than those actually  deducted on its books,
                  determined in accordance  with generally  accepted  accounting
                  principles;
 
                           (v) any additional amounts required to be paid during
                  such  period on account of taxes in respect of income  arising
                  prior to such  period  in excess of  reserves  for such  taxes
                  established out of income arising prior to such period; and
                           (vi)  any  additional  amounts  required  to be  paid
                  during  such period on account of  contract  renegotiation  or
                  price  redetermination  with  respect  to sales  prior to such
                  period   in  excess  of   reserves   for  such   renegotiation
                  established out of income arising prior to such period.
 
         Net Income  Available for Dividends of any  corporation for any period:
the Net  Income of such  corporation  for such  period  (excluding  any  amounts
included in the determination thereof on account of amounts repaid,  refunded or
credited  to such  corporation  during  such  period on account of taxes paid or
accrued in respect of income  arising prior to or during such period),  plus the
sum of all amounts deducted in the determination of such Net Income for
 
                  (a) interest  charges  on  indebtedness  accrued  during  such
         period;
 
 
                  (b)  amortization of debt discount applicable to such period;
 
                  (c)  provision  for taxes  imposed  on or  measured  by income
         determined after deduction of interest charges; and
 
                  (d) any  additional  amounts  required  to be paid during such
         period on account of taxes in respect of income  arising  prior to such
         period.
 
         Net Worth of any  corporation at any date: the sum of the capital stock
(excluding treasury stock and capital stock subscribed and unissued) and surplus
(including retained earnings and additional paid-in capital) of such corporation
as shown by the books of such corporation at such date.
 
         Parity  Stock:  any  stock  of  the  corporation  having  any  right or
preference  as to  dividends  or  assets  equal in any  respect  to any right or
preference of the $.70 Preferred Stock.
 
         Parity Stock  Payment:  any dividend or other  distribution,  direct or
indirect,  on or on account of any shares of any Parity Stock then or thereafter
outstanding, except a dividend payable solely in shares of Parity Stock, and any
redemption,  retirement,  purchase or other acquisition,  direct or indirect, of
any shares of any Parity Stock then or thereafter outstanding or of any warrants
or  rights  to  purchase  any  such  Stock,   except  to  the  extent  that  the
consideration  for any such  redemption,  retirement,  purchase  or  acquisition
consists of shares of Parity Stock.
<PAGE>
 
         Pro Forma Interest  and  Preferred  Dividends  at any date: the highest
aggregate amount
 
                  (a) all  interest  Charges  on   all   indebtedness   of   the
         corporation  and  its  Subsidiaries on a consolidated basis outstanding
         at such date, plus
 
                  (b) all  dividends  on the $.70  Preferred  Stock,  all Parity
         Stock and all Senior Stock,  multiplied by a fraction, the numerator of
         which is Consolidated  Net Income before provision for taxes imposed on
         or measured by income for the most  recently  completed  fiscal year of
         the  corporation,  and the  denominator  of which is  Consolidated  Net
         Income for such year,  payable or guaranteed,  after giving appropriate
         effect  to  immediately  proposed  transactions  at such  date,  by the
         corporation and its Subsidiaries  during the 12-month period commencing
         on  such  date  (or,  if the  aggregate  amount  of such  interest  and
         dividends so payable or  guaranteed  shall be greater  during any other
         12-month  period  commencing  after such date,  then  during such other
         12-month period).
 
         Purchase Agreements:  as defined in section 4.2 hereof.
 
         Securities Act:  as defined in section 4.2 hereof.
 
         Senior  Stock:  any  stock  of  the   corporation  having  any right or
preference  as to  dividends  or assets  senior in any  respect  to any right or
preference of the $.70 Preferred Stock.
 
         Subsidiary:  any  corporation  a majority  (by  number of votes) of the
Voting Stock of which is owned by the corporation or by one or more Subsidiaries
or by the corporation and one or more Subsidiaries.
 
         Voting  Stock,  when used with  reference  to any  corporation:  shares
(however  designated) of such  corporation  having ordinary voting power for the
election  of a  majority  of the  members  of the board of  directors  (or other
governing body) of such corporation, other than shares having such power only by
reason of the happening of a contingency.
 
         8.1.     Other Definitions.  As used  herein  the following  terms have
the following respective meanings:
 
 
<PAGE>
 
 
 
         "corporation"   shall,  where  the  context  so  permits,   include  an
association, joint stock company, business trust or other similar organization.
 
          "person" shall mean an individual,  a  corporation,  a partnership,  a
trust, an unincorporated organization or a government or any agency or political
subdivision thereof.
 
         "shares" of any corporation shall include any and all shares of capital
stock  of  such   corporation   of  any  class  or  other   shares,   interests,
participations or other equivalents  (however designated) in the capital of such
corporation.
 
         8.2. Accounting Terms and Principles.  All accounting terms used herein
which are not expressly defined herein shall have the respective  meanings given
to them  in  accordance  with  generally  accepted  accounting  principles,  all
computations  made pursuant  hereto shall be made in accordance  with  generally
accepted accounting principles and all financial statements shall be prepared in
accordance with generally accepted accounting principles.
 
                  (d)      So long as any shares of Preferred Stock of any 
                           series are outstanding:
 
                           (i)      Dividends on the  outstanding  Preferred 
                                    Stock of each series shall be declared and
                                    paid or set apart for payment  before any  
                                    dividends  shall be declared and paid or set
                                    apart for  payment on the Common  Stock with
                                    respect to the same quarterly dividend 
                                    period.  Dividends on any shares of 
                                    Preferred Stock shall be cumulative only if 
                                    and to the extent set forth in a certificate
                                    filed pursuant to law.  After  dividends  on
                                    all  shares of Preferred  Stock   (including
                                    cumulative  dividends  if and to the extent 
                                    any such  shares  shall be entitled thereto)
                                    shall  have been  declared  and paid or set 
                                    apart  for  payment  with respect to any  
                                    quarterly  dividend  period,  then and not 
                                    otherwise so long as any shares of the 
                                    Preferred  Stock shall remain  outstanding, 
                                    dividends may be declared and paid or set 
                                    apart for payment  with respect to the same 
                                    quarterly dividend  period  on the  Common  
                                    Stock out  of the  assets  or  funds  of the
                                    corporation legally available therefor.
<PAGE>
 
                                            All shares of Preferred Stock of all
                                    series  shall be of equal  rank,  preference
                                    and priority as to dividends irrespective of
                                    whether  or not the  rates of  dividends  to
                                    which the same  shall be  entitled  shall be
                                    the same and when the stated  dividends  are
                                    not paid in full,  the  shares of all series
                                    of the  Preferred  Stock shall share ratably
                                    in the payment  thereof in  accordance  with
                                    the  sums  which  would be  payable  on such
                                    shares  if all  dividends  were paid in full
                                    provided,  however,  that  any  two or  more
                                    series of the  Preferred  Stock  may  differ
                                    from  each  other  as to the  existence  and
                                    extent of the right to cumulative dividends,
                                    as aforesaid.
 
                           (ii)     In the event of any liquidation,  
                                    dissolution or winding up of the 
                                    corporation, whether  voluntary or  
                                    involuntary,  each series of Preferred Stock
                                    shall have preference  and  priority  over 
                                    the Common  Stock for  payment of the amount
                                    to which such series of Preferred  Stock  
                                    shall be entitled in accordance  with the
                                    provisions  thereof and each holder of 
                                    Preferred  Stock shall be entitled to be
                                    paid  in full  his  share  of such  amount, 
                                    or have a sum  sufficient  for the payment 
                                    in full set aside, before any payments shall
                                    be made to the holders of the Common  Stock.
                                    If, upon liquidation, dissolution or winding
                                    up of the corporation,  the assets of the 
                                    corporation or proceeds thereof, 
                                    distributable among the holders of the 
                                    shares of all series of the  Preferred Stock
                                    shall be insufficient  to pay, in full, the 
                                    preferential  amount  aforesaid,  then such
                                    assets,  or the  proceeds  thereof, shall be
                                    distributed  among such  holders ratably in 
                                    accordance  with the  respective  amounts 
                                    which would be payable if all amounts 
                                    payable  thereon  were  paid in full.  After
                                    the  payment  to the holders of Preferred  
                                    Stock of all such amounts to which they are 
                                    entitled, as above  provided,  the remaining
                                    assets and funds of the  corporation  shall 
                                    be divided and paid to the holders of the 
                                    Common Stock.
 
                  (e) Except as required by law or as determined by the Board of
Directors  pursuant to  subdivision  (b) of this Article  FOURTH,  the exclusive
rights to vote for the election of directors and for all other purposes shall be
vested in the  holders of Common  Stock,  each share  thereof  from time to time
outstanding having voting power of one vote.
<PAGE>
 
         FIFTH.  The minimum amount of capital with which the  corporation  will
commence  business is One Thousand Dollars ($1,000.00).
 
         SIXTH.  The corporation is to have perpetual existence.
 
         SEVENTH.  The  private  property  of the  stockholders  shall not be 
subject to the  payment of  corporate debts to any extent whatever.
 
         EIGHTH.  In furtherance and not in limitation of the powers  conferred 
by statute,  the board of directors is expressly authorized:
 
         To make, alter or repeal the by-laws of the corporation.
 
         To authorize and cause to be executed mortgages and liens upon the real
and personal property of the corporation.
 
         To set apart out of any of the funds of the  corporation  available for
dividends a reserve or reserves  for any proper  purpose and to abolish any such
reserve in the manner in which it was created.
 
         By resolution passed by a majority of the whole board, to designate one
or more committees, each committee to consist of two or more of the directors of
the  corporation,  which,  to the extent  provided in the  resolution  or in the
by-laws of the corporation,  shall have and may exercise the powers of the board
of directors in the  management of the business and affairs of the  corporation,
and may authorize the seal of the  corporation to be affixed to all papers which
may require it. Such  committee or  committees  shall have such name or names as
may be stated in the by-laws of the  corporation  or as may be  determined  from
time to time by resolution adopted by the board of directors.
 
         When and as  authorized  by the  affirmative  vote of the  holders of a
majority of the stock  issued and  outstanding  having  voting  power given at a
stockholders'  meeting duly called for that purpose,  or when  authorized by the
written  consent of the  holders of a majority  of the voting  stock  issued and
outstanding,  to sell,  lease or exchange  all of the property and assets of the
corporation,  including  its good will and its corporate  franchises,  upon such
terms and  conditions  and for such  consideration,  which may be in whole or in
part shares of stock in, and/or other  securities  of, any other  corporation or
corporations,  as its board of directors  shall deem  expedient and for the best
interests of the corporation.
 
         NINTH.  Meetings  of  stockholders  may be held  outside  the  State of
Delaware,  if the by-laws so provide.  The books of the  corporation may be kept
(subject  to any  provision  contained  in the  statutes)  outside  the State of
Delaware at such place or places as may be  designated  from time to time by the
board of directors or in the by-laws of the corporation.  Elections of directors
need not be by ballot unless the by-laws of the corporation shall so provide.
 
         TENTH. The corporation  reserves the right to amend,  alter,  change or
repeal any provision  contained in this  certificate  of  incorporation,  in the
manner now or hereafter  prescribed by statute,  and all rights  conferred  upon
stockholders herein are granted subject to this reservation.
 
                           4.  This  Restated  Certificate  of  Incorporation  
was  duly  adopted  by the  Board of Directors  of the  Corporation  in  
accordance  with  Section  245 of the General  Corporation  Law of the State of
Delaware.
<PAGE>
 
         IN WITNESS WHEREOF,  said HELIX TECHNOLOGY  CORPORATION has caused this
certificate  to be executed by Richard F. Cole,  President  of the  Corporation,
attested by Robert E. Blakelock,  Secretary of the Corporation, and affixed with
the corporate seal, this 4th day of February, 1980.
 
 
                         HELIX TECHNOLOGY CORPORATION
 
 
 
                         By  /s/ Richard F. Cole
                                 Richard F. Cole, President
 
[Seal]
 
ATTEST:
 
 
By /s/ Robert E. Blakelock,
         Robert E. Blakelock, Secretary