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                                                                     EXHIBIT 3.7

                          CERTIFICATE OF INCORPORATION

                                       OF

                        AMOSKEAG MANAGEMENT CORPORATION


         FIRST. The name of the corporation is AMOSKEAG MANAGEMENT
CORPORATION.

         SECOND. The address of its registered office in the State of Delaware
is Corporation Trust Center No. 1209 Orange Street, in the City of Wilmington,
County of New Castle, Delaware 19801. The name of its registered agent at such
address is The Corporation Trust Company.

         THIRD. The nature of the business or purposes to be conducted or
promoted is to engage in any lawful act or activity for which corporations may
be organized under the General Corporation Law of Delaware.

         FOURTH. The total number of shares of stock which the corporation
shall have authority to issue is two thousand (2,000) shares of common stock
without par value.

         The following restrictions are imposed upon the transfer of shares of
the capital stock of the corporation:

         The corporation shall have the right to purchase, or to direct the
transfer of, the shares of its capital stock in the events and subject to the
conditions and at a price fixed as provided below; each holder of shares of
such


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capital stock holds his shares subject to this right and by accepting the same
upon original issue or subsequent transfer thereof, the stockholder agrees for
himself, his legal representatives and assigns as follows:

         In the event of any change in the ownership of any share or shares of
such capital stock (made or proposed) or in the right to vote thereon (whether
by the holder's act or by death, legal disability, operation of law, legal
processes, order of court, or otherwise, except by ordinary proxies or powers
of attorney) the corporation has the right to purchase such share or all or any
part of such shares or to require the same to be sold to a purchaser or
purchasers designated by the corporation or to follow each such method in part
at a price per share equal to the fair value thereof at the close of business
on the last day next preceding such event as determined by mutual agreement or,
failing such agreement, by arbitration as provided below.

         In any such event the owner of the share or shares concerned therein
(being for the purposes of these provisions, all persons having any property
interest therein) shall give notice thereof in detail satisfactory to the
corporation. Within ten days after receipt of said owner's notice, the
corporation shall elect whether or not to


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exercise its said rights in respect to said shares and, if it elects to
exercise them, shall give notice of its election.

         Failing agreement between the owner and the corporation as to the
price per share to be paid, such price shall be the fair value of such shares
as determined by three arbitrators, one designated within five days after the
termination of said ten-day period by the registered holder of said share or
shares or his legal representatives, one within said period of five days by the
corporation and the third within five days after said appointment last
occurring by the two so chosen. Successor arbitrators, if any shall be
required, shall be appointed, within reasonable time, as nearly as may be in
the manner provided as to the related original appointment. No appointment
shall be deemed as having been accomplished unless such arbitrator shall have
accepted in writing his appointment as such within the time limited for his
appointment. Notice of each appointment of an arbitrator shall be given
promptly to the other parties in interest. Said arbitrators shall proceed
promptly to determine said fair value. The determination of the fair value of
said share or shares by agreement of any two of the arbitrators shall be
conclusive upon all parties interested in such

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shares. Forthwith upon such determination the arbitrators shall mail or deliver
notice of such determination to the owner (as above defined) and to the
corporation.

         Within ten days after agreement upon said price or mailing of notice
of determination of said price by arbitrators as provided below (whichever
shall last occur), the shares specified therein for purchase shall be
transferred to the corporation or to the purchaser or purchasers designated
therein or in part to each as indicated in such notice of election against
payment of said price at the principal office of the corporation.

         If in any of the said events, notice therefor having been given as
provided above, the corporation elects in respect of any such shares or any
part thereof not to exercise its said rights, or fails to exercise them or to
give notice or make payment all as provided above, or waives said rights by
vote or in authorized writing, then such contemplated transfer or such change
may become effective as to those shares with respect to which the corporation
elects not to exercise them or to give notice or to make payment, if
consummated within thirty days after such election, failure or waiver by the
corporation, or within such longer period as the corporation may authorize.

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     If the owner's notice in respect of any of such shares of capital stock is
not received by the corporation as provided above, or if the owner fails to
comply with these provisions in respect of any such shares in any other regard,
the corporation, at its option and in addition to its other remedies, may
suspend the rights to vote or to receive dividends on said shares, or may refuse
to register on its books any transfer of said shares or otherwise to recognize
any transfer or change in the ownership thereof or in the right to vote
thereon, one or more, until these provisions are complied with to the
satisfaction of the corporation; and if the required owner's notice is not
received by the corporation after written demand by the corporation it may also
or independently proceed as though a proper owner's notice had been received at
the expiration of ten days after mailing such demand, and, if it exercises its
rights with respect to said shares or any of them, the shares specified shall be
transferred accordingly.

     In respect of these provisions with respect to the transfer of shares of
capital stock, the corporation may act by its board of directors. Any notice or
demand under said provisions shall be deemed to have been sufficiently given if
in writing delivered by hand or addressed by mail



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postpaid, to the corporation at its principal office or to the owner (as above
defined) or to the holder registered on the books of the corporation (or his
legal representative) of the share or shares in question at the address stated
in his notice or at his address appearing on the books of the corporation.

     Nothing herein contained shall prevent the pledging of shares, if there is
neither a transfer of the legal title thereto nor a transfer on the books of
the corporation into the name of the pledgee, but no pledgee or person claiming
thereunder shall be entitled to make or cause to be made any transfer of
pledged shares by sale thereof or otherwise (including in this prohibition
transfer on the books of the corporation into the name of the pledgee) except
upon compliance herewith any such pledge shall be subject to those conditions
and restrictions.

     FIFTH. The name and mailing address of the sole incorporator is as follows:


          NAME                                    MAILING ADDRESS
          ----                                    ---------------

          Alan L. Lefkowitz                  Gaston Snow & Ely Barlett
                                             One Federal Street
                                             Boston, MA  02110


     SIXTH. The corporation is to have perpetual existence.



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     SEVENTH. In furtherance and not in limitation of the powers conferred by
statute, the board of directors is expressly authorized:

     To make, alter, amend, 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 a majority of the whole board, to designate one or more committees,
each committee to consist of one or more of the directors of the corporation.
The board may designate one or more directors as alternate members of any
committee, who may replace any absent or disqualified member at any meeting of
the committee. The by-laws may provide that in the absence or disqualification
of a member of a committee, the member or members thereof present at any meeting
and not disqualified from voting, whether or not he or they constitute a
quorum, may unanimously appoint another member of the board of directors to act
at the meeting in the place of any such absent or



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disqualified member. Any such committee, to the extent provided in the
resolution of the board of directors, or in the by-laws of the corporation,
shall have and may exercise all the powers and authority 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; but no such committee shall have the power or authority in
reference to amending the certificate of incorporation, adopting an agrement
of merger or consolidation, recommending to the stockholder the sale, lease or
exchange of all or substantially all of the corporation's property and assets,
recommending to the stockholders a dissolution of the corporation or a
revocation of a dissolution, or amending the by-laws of the corporation; and,
unless resolution or by-laws expressly so provide, no such committee shall have
the power or authority to declare a dividend or to authorize the issuance of
stock.

     When and as authorized by the stockholders in accordance with statute to
sell, lease or exchange all or substantially all of the property and assets of
the corporation, including its good will and it corporate franchises, upon such
terms and conditions and for such consideration, which may consist in whole or
in part of



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money or property including 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 interest of the corporation.

     EIGHT. Whenever a compromise or arrangement is proposed between this
corporation and its creditors or any class of them and/or between this
corporation and its stockholders or any class of them, any court of equitable
jurisdiction within the State of Delaware may, on the application in a summary
way of this corporation or of any creditor or stockholder thereof or on the
application of any receiver or receivers appointed for this corporation under
the provisions of Section 291 of Title 8 of the Delaware Code or on the
application of trustees in dissolution or of any receiver or receivers
appointed for this corporation under the provisions of Section 279 of Title 8
of the Delaware Code order a meeting of the creditors or class of creditors,
and/or of the stockholders or class of stockholders of this corporation, as the
case may be, to be summoned in such manner as the said court directs if a
majority in number representing three-fourths in value of the creditors or
class of creditors, and/or of the stockholders or class of stockholders of this
corporation, as the case may be, agree to any compromise or arrangement


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and to any reorganization of this corporation as consequence of such compromise
or arrangement, the said compromise or arrangement and the said reorganization
shall, if sanctioned by the court to which the said application has been made,
be binding on all the creditors or class of creditors, and/or on all the
stockholders or class of stockholders, of this corporation, as the case  may
be, and also on this corporation.

     NINTH. Meetings of stockholders may be held at such place, either within
or without the State of Delaware, as the by-laws may 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 written ballot unless the by-laws of the
corporation shall so provide.
     
     TENTH. The powers of the incorporator are to terminate upon the filing of
this certificate of incorporation with the Secretary of State of the State of
Delaware. The name and mailing address of the persons who are to serve as the
directors of the corporation, subject to the by-laws, until the first annual
meeting of stockholders or until their successors are elected and qualify are:


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            NAME                                MAILING ADDRESS
            ----                                ---------------

      Joseph B. Ely, II                         5 Webster Lane
                                                Wayland, MA 01778

      F. C. Dumaine                             201 Newton Street
                                                Weston, MA 02193

      W. Randle Mitchell, Jr.                   5 Webster Lane
                                                Wayland, MA 01778


     ELEVENTH. The corporation shall indemnify any person who was or is party
or is threatened to be made a party to any threatened, pending or completed
action, suit or proceeding, whether civil, criminal, administrative or
investigative (including an action by or in the right of the corporation) by
reason of the fact that he is or was a director, officer, employee or agent of
the corporation, or a stockholder purporting to act on behalf of the
corporation, or is or was serving at the request of the corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise, against expenses (including attorneys'
fees), judgments and fines actually imposed or reasonably incurred by him in
connection with such action, suit or proceeding unless in any proceeding he
shall be finally adjudged not to have acted in good faith and in a manner
reasonably believed to be in or not opposed to the best interest of the
corporation; provided, however, that such indemnification shall not cover
liabilities in connection


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with any matter which shall be disposed of through a compromise payment by such
person, pursuant to a consent decree or otherwise, unless such compromise shall
be approved as in the best interests of the corporation, after notice that it
involves such indemnification, (a) by a vote of the directors in which no
interested director participates, or (by) a vote or the written approval of the
holders of a majority of the outstanding stock at the time having the right to
vote for directors, not counting as outstanding any stock owned by any
interested director or officer. Such indemnification may include payment by the
corporation of expenses incurred in defending a civil or criminal action or
proceeding in advance of the final disposition of such action or proceeding,
upon receipt of an undertaking by the person indemnified to repay such payment
if he shall be adjudicated to be not entitled to indemnification under these
provisions. The termination of any action, suit or proceeding by judgment,
order, settlement, conviction, or upon a plea of nolo contendere or its
equivalent, shall not, of itself, create any presumption that the person did not
act in good faith and in a manner in which he reasonably believed to be in the
best interests of the corporation, and with respect to any criminal action or
proceeding, had reasonable cause to


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believe that his conduct was unlawful. The rights of indemnification hereby
provided shall not be exclusive of or affect other rights to which any
director, officer, employee, agent or stockholder may be entitled. As used in
this paragraph, the terms "director", "officer", "employee", "agent" or
"stockholder" include their respective heirs, executors and administrators, and
an "interested" director or officer is one against whom as such the proceeding
in question or another proceeding on the same or similar grounds is then
pending. Any indemnification to which a person is entitled under this paragraph
shall be provided although the person to be indemnified is no longer such a
director, officer, employee, agent or stockholder.

     TWELFTH. The corporation reserves the right to amend, alter, change or
repeal any provision contained in this certificate of incorporation, in the
manner now or thereafter prescribed by statute, and all rights conferred upon a
stockholder herein are granted subject to this reservation.
     
     I, THE UNDERSIGNED, being the sole incorporator hereinabove named, for the
purpose of forming a corporation pursuant to the General Corporation Law of the
State of Delaware, do make this certificate, hereby declaring and


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certifying that this is my act and deed and the facts herein stated are true,
and accordingly have hereunto set my hand this 14th day of December, 1984.


                                                  /s/ALAN L. LEFKOWITZ
                                                  --------------------------
                                                  Alan L. Lefkowitz





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