ASSUMPTION AND ASSIGNMENT AGREEMENT

     THIS AGREEMENT is made this 28th day of June, 1999 and effective on June
30, 1999, by and among PENNSYLVANIA INDUSTRIAL DEVELOPMENT AUTHORITY of
Harrisburg, Pennsylvania (hereinafter "PIDA"), MONTGOMERY COUNTY INDUSTRIAL
DEVELOPMENT CORPORATION, a non-profit corporation organized and existing under
the laws of the Commonwealth of Pennsylvania (the "Seller"), SLT PROPERTIES,
INC., a Delaware corporation, with an address of 147 Keystone Drive,
Montgomeryville, Pennsylvania 18936-9638 (the "Assignor") and LENFEST OAKS,
INC., a Pennsylvania corporation with an address of 200 Cresson Boulevard, P. O.
Box 989, Oaks, Pennsylvania 19456-0989 (the "Assignee");

     WHEREAS, pursuant to an Installment Sale Agreement dated September 14,
1990, as amended and restated by an Amended and Restated Installment Sale
Agreement dated November 25, 1991 (collectively the "Installment Sale
Agreement"), Seller, is the legal owner and Assignor is the equitable owner of
certain premises known as Lot #2, Oaks Corporate Center, Egypt Road and Route
422, Upper Providence Township, Montgomery County, Pennsylvania, more
particularly described in Exhibit "A" attached hereto and made a part hereof by
reference (hereinafter the "Premises"); and

     WHEREAS, Assignor and Assignee have entered into an Agreement of Sale dated
November 25, 1998, wherein Assignor has agreed to sell to Assignee, and Assignee
has agreed to purchase Assignor's equitable title to the Premises (as amended
the "Agreement of Sale"); and

     WHEREAS, pursuant to the Installment Sale Agreement, Seller executed and
delivered its Note dated November 20, 1991 and delivered December 2, 1991 in the
original principal amount of Two Million Dollars ($2,000,000.00) hereinafter the
"PIDA Note") in favor of (PIDA which was secured by a Mortgage on the Premises
executed by Seller dated November 20, 1991 and delivered December 2, 1991 (the
"Second Mortgage") and;

     WHEREAS, pursuant to the Installment Sale Agreement, Assignor agreed to
perform the obligations of the Seller under the PIDA Note and the Second
Mortgage; and

     WHEREAS, Assignee wishes to accept and assume all obligations of Assignor
in the Installment Sale Agreement and the PIDA Note and the Second Mortgage, as
well as the Loan Agreement between Seller and PIDA dated November 20, 1991
delivered December 2, 1991 and effective as of November 25, 1991, the Assignment
of Installment Sale Agreement between Seller, Assignor and PIDA dated November
20, 1991, and delivered December 2, 1991, the Consent, Subordination and
Assumption Agreement between Seller, Assignor and PIDA dated December 2, 1991
(collectively the "Loan Documents"); and

     WHEREAS, the Seller and PIDA wish to release Assignor from its obligations
under the Loan Documents (except that MCIDC does not release Assignor from
Assignor's rights, liabilities, responsibilities or obligations under the
Installment Sale Agreement) and permit Assignee to assume the rights and
obligations of Assignor under the Loan Documents;

     NOW THEREFORE, for good and valuable consideration tbe receipt and
sufficiency of which is hereby acknowledged by all parties and intending to be
legally bound hereby, all parties agree as follows:

     1. Assignor hereby grants, bargains, sells, assigns, transfers and sets
over unto Assignee and its heirs, personal representatives, successors and
assigns, all of the Assignor's right, title, and interest in, to and under the
Installment Sale Agreement.

                                        2
<PAGE>

     2. Assignee hereby assumes all liabilities and responsibilities and
obligations of Assignor under the Loan Documents arising from and after the
close of business on June 30, 1999, and agrees to be bound by any warrants of
attorney contained in the Loan Documents and the Installment Sale Agreement.

     3. Seller and PIDA hereby consent to said assignment by Assignor and
assumption by Assignee and from the date hereof forever discharge and release
Assignor of all rights, liabilities, responsibilities or obligations under the
Loan Documents which arise after the close of business on June 30, 1999 (except
that MCIDC does not release Assignor from Assignor's rights, liabilities,
responsibilities or obligations under the Installment Sale Agreement). From the
close of business on June 30, 1999, Assignor forever discharges and releases
Seller and PIDA of all rights, liabilities, responsibilities and obligations
under the Assignment and Assumption Agreement, Installment Sale Agreement and
the Loan Documents.

     4. Assignee hereby indemnifies Seller from any damages, fees, costs or
attorney's fees incurred by Assignee as a result of the transaction contemplated
herein.

     5. Assignee has knowingly and voluntarily entered into this Agreement and
acknowledges that the ensuing Paragraph 6 sets forth a warrant of authority for
an attorney to confess judgment against Assignee. In granting this warrant of
attorney to confess judgment against Assignee, Assignee after reviewing the same
and being counseled by separate counsel of Assignee, hereby knowingly,
intentionally, voluntarily and unconditionally waives any and all rights that
Assignee has or may have to prior notice and an opportunity for hearing under
the respective constitutions and laws of the United States and the Commonwealth
of Pennsylvania

     6. UPON THE OCCURRENCE OF AN EVENT OF DEFAULT UNDER THE INSTALLMENT SALE
AGREEMENT OR ANY OF THE LOAN DOCUMENTS.

                                        3
<PAGE>

OF ANY COURT OF RECORD IN PENNSYLVANIA OR ELSEWHERE TO APPEAR FOR AND CONFESS
JUDGMENT AGAINST ASSIGNEE FOR ALL AMOUNTS FOR WHICH ASSIGNEE MAY BE OR BECOME
LIABLE TO SELLER OR ITS ASSIGNEE UNDER THIS AGREEMENT AS EVIDENCED BY AN
AFFIDAVIT SIGNED BY AN OFFICER OF SELLER OR ITS ASSIGNEE, SETTING FORTH THE
AMOUNTS THEN DUE PLUS REASONABLE ATTORNEY FEES, WITH COSTS OF SUIT AND RELEASE
OF ERRORS. SUCH AUTHORITY SHALL NOT BE EXHAUSTED BY ANY ONE EXERCISE THEREOF BUT
JUDGMENT MAY BE CONFESSED AS AFORESAID FROM TIME TO TIME AS OFTEN AS THERE IS A
DEFAULT HEREUNDER AND A COPY OF THIS AGREEMENT SHALL BE HIS SUFFICIENT WARRANT,

     7. This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same Agreement.

     IN WITNESS WHEREOF, the parties have set their hands and seals this 28th
day of June, 1999.

ATTEST:                            ASSIGNOR:
                                   SLT PROPERTIES, INC.

/s/ Craig K. Carra                 By: /s/ Davis Woodward
    ---------------------------            ------------------------------
    Craig K. Carra, Ass't Sec'y            Davis Woodward, Vice President

                                   ASSIGNEE:
                                   LENFEST OAKS, INC.

_______________________________    By: __________________________________


ATTEST:                            ASSIGNOR:
                                   SLT PROPERTIES, INC.

_______________________________    By: __________________________________

                                   ASSIGNEE:
                                   LENFEST OAKS, INC.

/s/ Mark H. Fisher                 By: /s/ Maryann V. Bryla
    ---------------------------            --------------------------------
    Mark H. Fisher                         Maryann V. Bryla
    Assistant Secretary                    Vice President


                    [SIGNATURES CONTINUED ON FOLLOWING PAGE}

                                        4
<PAGE>

                    [SIGNATURES CONTINUED FROM PREVIOUS PAGE]

                                   MONTGOMERY COUNTY INDUSTRIAL
                                   DEVELOPMENT CORPORATION

___________________________        By: /s/ Carmen S. Italia, Jr., President
                                           --------------------------------
                                           Carmen S. Italia, Jr., President

                                   PENNSYLVANIA INDUSTRIAL
                                   DEVELOPMENT AUTHORITY (PIDA)

/s/ Evelyn Shepley                 By: /s/ Marguerite Harris
    -------------------                ---------------------
    Evelyn Shepley                         Marguerite Harris
    Assistant Secretary                    Administrator

                                       5
<PAGE>


COMMONWEALTH OF PENNSYLVANIA:
                             ss
COUNTY OF MONTGOMERY        :

     On the 28th day of June A.D., 1999, before me, the subscriber, a Notary
Public, personnally appeared Davis Woodward, who acknowledges himself to be the
Vice President of SLT PROPERTIES, INC., a Delaware corporation, and that he, as
such officer, being authorized to do so, executed the foregoing instrument by
signing the name of the Corporation by himself as and for the act and deed of
said Corporation for the uses and purposes therein contained and that he
desires the same might be recorded as such.

     IN WITNESS WHEREOF, I have hereunto set my official hand and seal.

                          /s/ Patricia A. Moriarty
                              --------------------
                              Notary Public

                                  Notary Seal
                      Patricia A. Moriarty, Notary Public
                       Montgomery Twp., Montgomery County
                       My Commission Expires May 20, 2002

                                       6
<PAGE>

COMMONWEALTH OF PENNSYLVANIA:
                             ss
COUNTY OF MONTGOMERY        :

     On the 29th day of June A.D., 1999, before me, the subscriber, a Notary
Public, personally appeared Maryann V. Bryla, who acknowledges herself to be
the Vice President of LENFEST OAKS, INC., a Pennsylvania corporation, and that
she, as such officer, being authorized to do so, executed the foregoing
instrument by signing the name of the Corporation by herself as and for the act
and deed of said Corporation for the uses and purposes therein contained and
that she desires the same might be recorded as such.

     IN WITNESS WHEREOF, I have hereunto set my official hand and seal.

                          /s/ Julie B. Duffy
                              --------------
                              Notary Public

                                  Notary Seal
                          Julie B. Duffy, Notary Public
                    Upper Providence Twp., Montgomery County
                       My Commission Expires Oct. 22, 2001

                                       7
<PAGE>

COMMONWEALTH OF PENNSYLVANIA:
                             ss
COUNTY OF MONTGOMERY        :

     On the 28th day of June A.D., 1999, before me, the subscriber, a Notary
Public, personally appeared CARMEN S. ITALIA, JR., who acknowledges himself to
be the President of MONTGOMERY COUNTY INDUSTRIAL DEVELOPMENT CORPORATION, and
that he, as such officer, being authorized to do so, executed the foregoing
instrument by signing the name of the Corporation by himself as and for the act
and deed of said Corporation for the uses and purposes therein contained and
that he desires the same might be recorded as such.

     IN WITNESS WHEREOF, I have hereunto set my official hand and seal.

                          /s/ Deborah A. Mader
                              ----------------
                              Notary Public

                                  Notary Seal
                         Deborah A. Mader, Notary Public
                      Upper Gwynedd Twp., Montgomery County
                       My Commission Expires Oct. 8, 2001

                                       8
<PAGE>

COMMONWEALTH OF PENNSYLVANIA:
                             ss
COUNTY OF DAUPHIN           :

     On the 28th day of June A.D., 1999, before me, the subscriber, a Notary
Public, personally appeared MARGUERITE HARRIS, who acknowledges herself to be
the Administrator of PENNSYLVANIA INDUSTRIAL DEVELOPMENT AUTHORITY, and that
she, as such officer, being authorized to do so, executed the foregoing
instrument by signing the name of the Corporation by herself as and for the act
and deed of said Corporation for the uses and purposes therein contained and
that she desires the same might be recorded as such.

     IN WITNESS WHEREOF, I have hereunto set my official hand and seal.

                          /s/ Heather L. Hinton
                              -----------------
                              Notary Public

                                  Notary Seal
                        Heather L. Hinton, Notary Public
                       City of Harrisburg, Dauphin County
                       My Commission Expires Jan. 6, 2003

                                       10
<PAGE>

                                   EXHIBIT "A"

ALL THAT CERTAIN tract of land situate in the Township of Upper Providence,
County of Montgomery, Commonwealth of Pennsylvania, as shown on Final
Subdivision Plan prepared for Acorn Development Corporation (Sheet 1 of 1) by
Pennoni Associates, Inc., Consulting Engineers, 1611 Arch Street, Philadelphia,
Pennsylvania 19103 and Yerkes Associates, Inc., 101 Charles Street, Box 1080,
Bryn Mawr, Pennsylvania 19101 recorded on September 11, 1990 in the Office of
the Recorder of Deeds in and for Montgomery County in Plan Book A-52, page 198,
bounded and described as follows, to wit:

BEGINNING at a point in the title line of Mill Road, said point being located
North 06 degrees 37 minutes 54 seconds West 509.00 feet from the intersection of
said title line with the centerline of Cresson Boulevard (50 feet wide); thence
extending along said title line of Mill Road North 06 degrees 37 minutes 54
seconds West 394.00 feet to a point in line of lands of Burl L. and Geraldine
Collins; thence extending along said lands the following 02 courses and
distances: (1) North 73 degrees 16 minutes 45 seconds East 216.79 feet to a
point; (2) North 06 degrees 37 minutes 55 seconds West 135.95 feet to a point in
the Southeasterly title line of Egypt Road, S.R. 46062-2; thence extending along
said title line North 80 degrees 10 minutes 00 seconds East 68.97 feet to a
point in the centerline of Cresson Boulevard, thence extending along said
centerline the following 03 dimensions: (1) South 39 degrees 00 minutes 00
seconds East 146.56 feet to a point of curvature; (2) extending along the arc of
a circle curving to the right, having a radius of 225.00 feet, the arc distance
of 131.55 feet to a point of tangency; (3) crossing a 25 foot wide storm
easement South 05 degrees 30 minutes 00 seconds East 323.16 feet to a point in
line of Lot No. 3; thence extending along said Lot South 83 degrees 22 minutes
06 seconds West 389.29 feet to the point and place of BEGINNING.

CONTAINING 4.147 acres of land, more or less.

BEING Lot 2 as shown on the above mentioned Plan

PARCEL NUMBER: 61-00-01208-14-4.

BEING the same premises which Oaks Associates, a Pennsylvania Limited
Partnership by Indenture dated September 14, 1990 and recorded in the Office of
the Recorder of Deeds in and for the County of Montgomery in Deed Book 4958 Page
199, granted and conveyed unto Montgomery County Industrial Development
Corporation, a Pennsylvania Non-Profit Corporation.