EXH2-4

                            PURCHASE & SALE AGREEMENT

                             BETWEEN ALT AND NORSCAN


         AGREEMENT,  made as of this 7th day of September,  1986, by and between
Norscan Instruments,  Ltd., a Canadian corporation having its principal place of
business at Winnipeg,  Manitoba,  Canada  (hereinafter  "Norscan") and Automated
Light Technologies,  Inc. a Delaware corporation,  having its principal place of
business at Sturbridge, Massachusetts 01566 (hereinafter "ALT").


                                   WITNESSETH:


         WHEREAS,  FOCMS, a fiber optic cable  monitoring  system,  is a new and
useful  technology  and all the uses of FOCMS have not been  identified or fully
explored;

         WHEREAS, ALT is a recently formed corporation;

         WHEREAS,  it is the  desire  of  ALT to  engage  in  R&D,  Engineering,
Manufacturing,  and Sales  activities  with  respect to  applications  for FOCMS
worldwide (except Canada);

         WHEREAS,  ALT expects  that such  activities  will result in  specially
constructed or developed FOCMS; WHEREAS,  Norscan owns patents relating to FOCMS
in the United Kingdom and the United States (see Appendix);

         WHEREAS,  ALT plans to investigate  and manufacture  specialized  FOCMS
which may be impeded in the absence of patented  inventions and related know-how
technology from Norscan;

         WHEREAS,  Norscan desires that FOCMS know-how technology be advanced as
quickly as possible  and its  patented  inventions  be used to promote,  and not
hinder, such advancement;

         WHEREAS,  Norscan's  know-how  technology  may  assist  ALT to  develop
specially constructed FOCMS; and

         WHEREAS, for the foregoing reasons, ALT has offered to purchase patents
and know-how  from Norscan for  worldwide  sale and use (except  Canada),  under
Norscan  patents and  know-how  technology  whereby ALT may pursue its plans and
desires and Norscan is willing to sell such patents and know-how.

         NOW, THEREFORE, in consideration of the grants, covenants, and promises
herein contained, Norscan and ALT agree as follows


         ARTICLE I - DEFINITIONS

         The following  terms,  whenever used in this Agreement,  shall have the
meaning set forth below:


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         A. "FOCMS"  shall mean all methods and  apparatus for fiber optic cable
monitoring  systems developed or acquired,  by Norscan.  Such FOCMS instruments,
components,  or  systems  may be  leased,  sold,  and  used  in any  appropriate
application  including but not limited to the fields of  Telecommunications  and
Data communica-tions.

         B.  "Norscan  Patents"  shall mean each foreign  patent  (non-Canadian)
filed or acquired by Norscan  which relates to FOCMS and which has a filing date
or acquisition date prior to September 1, 1991.

         C. "Norscan  Know-How"  shall mean  technical  information  of any kind
relating to the manufacture, use or sale of FOCMS and which is owned by Norscan.

         ARTICLE II - PATENT ASSIGNMENT

         A. Norscan assigns to ALT all rights, title and interest to each of the
foreign "Norscan Patents" and foreign Patent  Applications  filed and unfiled in
consideration for which ALT grants to Norscan 150 shares of common stock of ALT.
(At  present,  there are 3,000  shares of ALT  common  stock  issued.)  Executed
Assignments  of U.K.  Patent  2,082,406  and U.S.  Patent  4,480,251  are  being
prepared by Norscan for prompt  transmittal to ALT. All "Norscan Patents" having
a filing date or  acquisition  date prior to  September 1, 1991 will be promptly
assigned to ALT at the time of filing or acquisition.

         B. All future costs for (a) maintaining  issued foreign patents and (b)
filing, prosecuting and maintaining future foreign applications shall be paid by
ALT . Norscan will provide ALT with all necessary  assistance from the inventors
in the filing and prosecution of all foreign patent applications .

         ARTICLE III - KNOW-HOW

         A. NORSCAN KNOW-HOW

         It is in  the  interest  of  ALT,  Norscan  and  the  public  that  the
development  work of ALT not be impeded  because  ALT does not  possess  certain
know-how. To avoid such impediment, the parties agree that Norscan shall provide
to ALT all technical  know-how  information  required to develop and manufacture
all components and related  products defined as FOCMS.  This technical  know-how
information  includes  but is not limited to drawings,  blueprints,  part lists,
vendor's lists, etc. . Furthermore, the parties agree that their representatives
shall meet periodically for the purpose of discussing  current  development work
at ALT and Norscan with respect to FOCMS.  ALT and Norscan agree that:  (1) When
such meetings are convened, each party shall be free to designate its respective
representative or  representatives;  and (2) Each party shall be free to require
that such  discussions  shall be subject to and  conditioned  upon  conventional
non-disclosure  agreements,  copies of which are  attached  hereto.  Either as a
result of such  discussions  or  otherwise,  (1) ALT may  request  that  Norscan
provide to ALT such  know-how as Norscan may have with  respect to a  particular
FOCMS,  or (2) Norscan  may offer to supply to ALT such  know-how as Norscan has
and wishes to provide with respect to a particular FOCMS.


<PAGE>




         ARTICLE IV - ASSIGNMENT

         This Agreement can be assigned by ALT to its subsidiaries.

         ARTICLE V - TERMS AND CONDITIONS

         A.  Norscan  shall not provide  know-how,  patent  rights or in any way
directly or indirectly  compete with ALT worldwide  (except Canada) in the FOCMS
products  and  applications  as covered  under the Norscan  Patents  (defined in
Article I-C).

         B. Norscan shall obtain clearance from the ALT corporate counsel or Dr.
Mohd A. Aslami and Mr. Charles DeLuca  (jointly) prior to the sale of any of its
shares in ALT that it has met all of its  obligations  under this  purchase  and
sale  agreement,  for sales prior to September 1, 1991. For sale after September
1, 1991 , Norscan stall obtain only ONE clearance from ALT corporate  counsel or
Dr. Mohd A. Aslami and Mr. Charles DeLuca (jointly) that Norscan has met all its
obligations  to ALT under this  Purchase  and Sale  Agreement up to September 1,
1991.  If Norscan's  request for clearance to sell shares in ALT either prior to
or after  September 1, 1991 is withheld by ALT corporate  counsel or Mohd Aslami
and Charles  DeLuca as provided  herein,  then the  clearance  request  shall be
submitted  for  resolution to  arbitration  subject to the rules of the American
Arbitration Association.

         C. Mr. David Vokey of Route 5, Hickory,  N.C.  28601,  a co-inventor of
Norscan patents and a principal stockholder of Norscan agreed to join ALT at its
request under a mutually and reasonably agreed upon compensation plan.

         D. Mr. Ken Sontag of 11  Bluegrass  Road,  Winnipeg,  Manitoba,  Canada
R2C-2Z2,  a principal  stockholder  of Norscan agrees to join ALT at its request
(within one month)  under a mutually  and  reasonably  agreed upon  compensation
plan.

         ARTICLE VI - COMMUNICATIONS

         All notices and reports to be  delivered  to ALT and Norscan  under the
terms of this  Agreement  shall be considered  as so delivered  when sent to the
other party by registered mail, postage prepaid,  at the address hereinafter set
forth, or to such other addresses as may subsequently be designated in writing:

                  Norscan Instruments, Ltd.
                  P.O. Box 44
                  Winnipeg, Manitoba
                  Canada R3C-2G1

                  Attention: President

                  ALT, Inc.
                  P.O. Box 945
                  Sturbridge, Massachusetts 01S66

                  Attention: President


<PAGE>




         ARTICLE VII - MISCELLANEOUS

         A. Nothing in this  Agreement  is to be construed  as, nor is there any
other agreement  between the parties which is to be construed as, an undertaking
by either  party to refrain from doing any act as to which a patent right is not
granted by this Agreement.

         B. This  Agreement  has been entered into in, and shall be construed in
accordance with the laws of the State of Massachusetts.

         C. This  Agreement  may not be waived,  altered or  modified  except by
written agreement of the parties.

         D. A waiver or any breach of any  portion of this  Agreement  shall not
constitute a waiver of a prior,  concurrent or subsequent  breach of the same or
any  other  provision  hereof  and a waiver  shall  not be  effective  unless in
writing.  In the event that any  provision of this  Agreement  shall be declared
unenforceable,  such provision shall be severed and the balance of the Agreement
shall continue in full force and effect.

         E.  Neither  Norscan  nor ALT shall  make any  press or public  release
concerning  this  Agreement  except in form  agreed to in  writing  by the other
party;  provided,  however,  neither  party shall be  precluded  from making any
disclosure  concerning this Agreement  which is deemed  necessary to comply with
the law. Any reference to or description of this Agreement  which ALT desires to
appear in any registration statement or offering by or on behalf of ALT shall be
an accurate reference or description,  consisting of material  information.  ALT
and  Norscan  shall not  otherwise  disclose  the terms and  conditions  of this
Agreement  to any third party  without the prior  written  consent of the other;
provided,  however, that: (a) ALT may, in connection with any public offering or
private placement by ALT, disclose the terms and conditions of this Agreement to
underwriters and placement agencies associated therewith, and (b) Norscan, after
providing  written notice to ALT, shall have the right to disclose the terms and
conditions of this Agreement to a third party,  with whom it is having licensing
negotiations  and subject to a non-disclosure  agreement,  that lasts as long as
this  agreement  is  confidential,  and  shall  have the right to  produce  this
Agreement in connection  with any  litigation  to which it is a party,  provided
that such  production  is subject to a protective  order,  that lasts as long as
this Agreement is confidential, entered by the Court.

         F. The headings of this Agreement are intended  solely for  convenience
of reference and shall be given no effect in the construction or  interpretation
of this Agreement.

         ARTICLE VIII - ENTIRE AGREEMENT

         The  terms  and  provisions  herein  contained  constitute  the  entire
agreement between the parties relating to the patent rights and know-how granted
herein and supersede all previous communications, representations, agreements or
understandings,  either  oral or  written,  between  the  parties  with  respect
thereto.  Any  modifications  of this  Agreement  shall not be effective  unless
signed by duly authorized officers or representatives of the parties.


<PAGE>



         ARTICLE IX - FORCE MAJEURE

         If the performance of any obligation  under this Agreement is prevented
by any cause  beyond  the  reasonable  control of a party,  such party  shall be
excused  from  such  performance  for so long as is  reasonable.  The  party  so
prevented shall use all practical  efforts to perform its obligations as soon as
possible.

         IN WITNESS THEREOF, the parties have caused this Agreement to be signed
by their  respective  authorized  officers  as of the day and year  first  above
written.

         Norscan Instruments, Ltd.           Norscan Instruments, Ltd.

         By__/S/____________ _____           By___/S/___________ _____
           Secretary         Date              President          Date

ALT, Inc.

         By__/S/____________ _____           By___/S/___________ _____
           Secretary         Date              President          Date



<PAGE>



                                    APPENDIX

                             Norscan Foreign Patents


(1)      U.K. Patent 2,082,406B entitled -

         MONITORING ELECTRICAL CABLES AND JOINTS
         FOR THE INGRESS OF MOISTURE
         by David Ernest Vokey
            John Paul McNaughton
            Wayne Edward Domenco

(2)      U.S. Patent 4,480,251 issued October 30, 1984 entitled -

         APPARATUS TO MONITOR ELECTRICAL CABLES, INCLUDING SPLICE
         JOINTS AND THE LIKE, FOR THE INGRESS OF MOISTURE
         by John P. McNaughton
            Wayne E. Domenco
            David E. Vokey

(3) Norscan  Foreign  Patent  Applications  relating to FOCMS  acquired or filed
prior to September 1, 1991.


<PAGE>



NORSCAN  INSTRUMENTS  LTD., 11 Bluegrass  Road,  Winnipeg,  Manitoba,  Canada in
consideration  of One Dollar ($1.00) and other good and valuable  consideration,
the  receipt  of which is  hereby  acknowledged,  do hereby  sell and  assign to
AUTOMATED   LIGHT   TECHNOLOGIES   INC.,   7  Laurel   Hill  Road,   Sturbridge,
Massachusetts,  USA, hereinafter called the assignee,  the entire,  right, title
and interest in and to the invention  entitled  "APPARATUS TO MONITOR ELECTRICAL
CABLES,  INCLUDING  SPLICE JOINTS AND THE LIKE, FOR THE INGRESS OF MOISTURE " as
disclosed in the United States Patent No. 4,480,251 issued the 13th day of June,
1984 and in and to any and all reissues and extensions  thereof,  in and for the
United Kingdom, and all other countries in the world save and except Canada, the
same to be held and enjoyed by the said assignee,  its successors,  assigns,  or
legal representatives to the full ends of the terms for which all Letters Patent
therefor are granted, as fully and entirely as the same would have been held and
enjoyed by us if this  assignment  and sale had not been made,  this  assignment
including the right to take action and recover in respect of any infringement of
the patent that took place prior to the date of this assignment.

SIGNED at the City of Winnipeg,  in the Province of Manitoba,  Canada, this 13th
day of February, 1987.


                                           NORSCAN INSTRUMENTS LTD.

                                           PER:___/S/______________ Pres.

                                           PER:___/S/______________ Sec.


<PAGE>



NORSCAN  INSTRUMENTS  LTD., 11 Bluegrass  Road,  Winnipeg,  Manitoba,  Canada in
consideration  of One Dollar ($1.00) and other good and valuable  consideration,
the  receipt  of which is  hereby  acknowledged,  do hereby  sell and  assign to
AUTOMATED   LIGHT   TECHNOLOGIES   INC.,   7  Laurel   Hill  Road,   Sturbridge,
Massachusetts,  USA, hereinafter called the assignee,  the entire,  right, title
and interest in and to the invention  entitled  "APPARATUS TO MONITOR ELECTRICAL
CABLES,  INCLUDING  SPLICE JOINTS AND THE LIKE,  FOR THE INGRESS OF MOISTURE" as
disclosed in the United  Kingdom Patent No. 2082406 issued the 13th day of June,
1984 and in and to any and all patents of confirmation  and extensions  thereof,
in and for the United  Kingdom,  and all other  countries  in the world save and
except  Canada,  the  same to be held and  enjoyed  by the  said  assignee,  its
successors,  assigns, or legal representatives to the full ends of the terms for
which all Letters Patent therefor are granted, as fully and entirely as the same
would have been held and enjoyed by us if this  assignment and sale had not been
made, this assignment  including the right to take action and recover in respect
of any  infringement  of the patent  that took  place  prior to the date of this
assignment.

SIGNED at the City of Winnipeg,  in the Province of Manitoba,  Canada, this 13th
day of February, 1987.


                                           NORSCAN INSTRUMENTS LTD.

                                           PER:___/S/______________ Pres.

                                           PER:___/S/______________ Sec.