Exhibit 10.4



      ASSIGNMENT OF INTELLECTUAL PROPERTY AND TRANSFER OF RIGHTS AGREEMENT


This  Assignment of Intellectual Property and Transfer of Rights Agreement (this
      "Agreement")  is made and  entered  into as of  September  23,  1998  (the
      "Effective Date") by and between Sierra Monitor Corporation,  a California
      corporation with principal offices at 1991 Tarob Court, Milpitas, CA 95035
      (the  "Company")  and Edward  Hague,  an  individual  ("Seller")  who is a
      California  resident.   Each  of  the  Company  and  Seller  is  sometimes
      hereinafter referred to as a "Party" and, collectively, they are sometimes
      hereinafter referred to as "the Parties".

                                    RECITALS:

         WHEREAS,   Seller   now   owns  a  line  of   products   known  as  the
"Communications  Bridge", as more fully described on the List of Assets attached
hereto as Exhibit A (the "Communications Bridge.")

         WHEREAS,  for  purposes  of this  Agreement,  the  product and the term
"Communications  Bridge" shall  include all right,  title and interest in and to
the Communications Bridge,  including,  but not limited to, all related computer
programs  (including  the  underlying  source code and object  code),  software,
customer lists,  intellectual  property and all other rights developed by, owned
by, or otherwise granted to, Seller;

         WHEREAS,  the  Company now desires to acquire all rights from Seller to
the Communications  Bridge, so that the Company can manufacture,  distribute and
sell the  Communications  Bridge as well as to further develop such products and
related products;

         WHEREAS,  the Company now desires to  purchase,  and Seller  desires to
sell, the Communications  Bridge in exchange for a cash payment and unregistered
shares of the Company's common stock; and

         NOW,  THEREFORE,  in  consideration  of the  foregoing  and the  mutual
covenants  and  promises  contained  herein  and for  other  good  and  valuable
consideration, the Company and Seller agree, as follows:

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<PAGE>


                                  Exhibit 10.4

                                   AGREEMENT:

         1.       Sale, Assignment and Transfer of the Communications Bridge.

                  (a)  Intellectual  Property  and  Rights  Transferred.  Seller
hereby grants and irrevocably assigns all right, title and interest  whatsoever,
throughout  the world,  in and to the computer  programs,  software,  source and
object code, documentation,  and all other rights owned by, or otherwise granted
to, Seller known as the Communications  Bridge,  including,  without limitation,
the  rights  and works  specifically  listed on  Exhibit A hereto as well as all
intellectual property rights, including but not limited to, copyrights, patents,
trademarks and trade secrets associated with the  Communications  Bridge, to the
Company,  its successors and assigns,  for the full duration of all such rights,
and  any  renewals  and   extensions   thereof.   The  Parties  agree  that  the
Communications  Bridge to be  transferred  shall  include  all  related  support
materials,  work-in-progress  and documentation owned by Seller including notes,
records, sketches, drawings,  specifications,  and any other material related to
the Communications Bridge. Such transferred Communications Bridge, including all
such support materials and  documentation,  will remain the sole property of the
Company.

                  (b) Computer  Programs and Software  Transferred.  The Parties
agree  that such  computer  programs  and  software  transferred  as part of the
Communications  Bridge  assigned to the  Company  shall  include the  underlying
source  code as  written  in the  programming  language  used by  Seller  in its
original  development.  In  addition,  the Parties  agree  that,  except for the
representations,   warranties,   agreements  and  covenants  contained  in  this
Agreement,  Seller is  providing  such  computer  programs  and  software to the
Company on an "as is" basis with no warranty that such  programs are  error-free
and without any express or implied warranty of  merchantability or fitness for a
particular  purpose  and with no ongoing  maintenance  or  support  obligations.
Seller further agrees that the Company shall have the right to alter,  modify or
combine the transferred  computer  programs,  software and other portions of the
Communications Bridge with other works, and hereby waives any claim that any new
versions,  developments or derivative works involving the Communications  Bridge
constitutes  a violation of any "moral  rights" or a  distortion,  mutilation or
disparagement  or  contains  unauthorized  variations  of  the  same.  As of the
Effective  Date,  the Company shall assume all costs of the further  development
and support of the  Communications  Bridge,  including  those  related,  but not
limited to, salaries, consulting services and equipment; however, nothing herein
shall  require or otherwise  obligate the Company to assume any  obligations  or
liabilities of Seller, or to continue the production,  sales and/or  development
of the Communications Bridge.

                  (c) Cooperation in Securing  Rights.  Seller hereby  covenants
and agrees that he will assist and cooperate with the Company,  or its designee,
in every proper way to further secure the Company's rights in the Communications
Bridge hereby  assigned to the Company  together with any  copyrights,  patents,
trademarks, trade secrets or other intellectual property rights relating thereto
in any and all  countries.  Such  cooperation  and  assistance  of Seller  shall
include, but not be limited to, the giving of testimony and the prompt execution
of  all  applications,   specifications,   oaths,   assignments  and  all  other
instruments  which the Company deems  necessary in order to apply for,  perfect,
obtain and sustain such intellectual  property rights and in order to assign and
convey to the  Company,  its  successors,  assigns,  and  nominees  the sole and
exclusive right,  title and interest in and to such  transferred  Communications
Bridge  and  any  copyrights,   patents,  trademarks,  trade  secrets  or  other
intellectual  property  rights  relating  thereto,   including  the  filing  and
prosecution of  substitute,  divisional,  continuing or additional  applications
covering  said  intellectual  property  rights,  including  without  limitation,
reissues and reexaminations,  opposition proceedings,  cancellation proceedings,
priority  contests,  public  use  proceedings,  infringement  actions  and court
actions; provided,  however, that if Seller is not then employed by the Company,
the Company  shall  reimburse  Seller for his  reasonable  time, on the basis of
Seller's then current  standard  consulting  rates as determined by reference to
the rates  actually  charged by Seller to his other then  current  clients,  and
expenses in connection with providing such cooperation.

                  (d) Validity of the Transfer of Communications  Bridge. Seller
represents and warrants (i) that Seller has not previously granted any rights in
the  Communications  Bridge to any third party  (which have not  otherwise  been
reacquired in full by Seller prior to the Effective  Date); and (ii) that Seller
currently has the full power and authority to make and enter into this Agreement
and to make the present assignment of the

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<PAGE>
                                  Exhibit 10.4

Communications  Bridge to the Company as  contemplated  by this  Agreement.  The
Company  represents  and  warrants to Seller (i) that the Company has the right,
power and authority to enter into and fully perform its  obligations  hereunder;
and (ii) the making of this  Agreement by the Company does not violate any other
agreement between the Company and any third party.

         2.   Consideration.   Upon  the   execution  of  this   Agreement   and
contemporaneous  with the transfer of the Communications  Bridge to the Company,
the Company will simultaneously,  or as soon as practical thereafter, deliver to
Seller (i) a certificate  registered in Seller's name  representing  Two Hundred
Eleven Thousand Three Hundred and Twenty-Five  (211,325)  unregistered shares of
the Company's  common stock (the "Shares") and (ii) a check (or checks)  payable
to Seller for a total of One  Hundred  and  Thirty  Thousand  and Three  Hundred
Dollars (U.S. $130,300,  the "Payment").  Such Payment shall be inclusive of all
applicable  taxes,  fees or  other  assessments,  if  any,  involved  with  this
transfer.  In addition,  such Payment shall be inclusive of any expenses or fees
of any nature whatsoever,  claimed or to be claimed by Seller in connection with
the  preparation  of this  Agreement  or  involved  with  the  transfer  of such
Communications Bridge to the Company.

         3.  Representations.  The Seller agrees that he will execute any proper
oath or  verify  any  proper  document  required  to carry out the terms of this
Agreement.  The  Seller  agrees  that his  performance  of all the terms of this
Agreement will not breach any other agreement to keep in confidence  proprietary
information acquired by him in confidence or in trust prior to his employment by
the Company.  The Seller hereby agrees,  represents and warrants that he has not
entered into, and will not enter into, any oral or written agreement in conflict
with this Agreement.

         4.  Acquisition  of Shares  of Common  Stock.  In  connection  with his
acquisition  of the  Shares  of  common  stock  of the  Company,  Seller  hereby
represents to the Company the following:

                  (a)  Seller is aware of the  Company's  business  affairs  and
financial condition and has acquired sufficient information about the Company to
reach an informed and knowledgeable  decision to acquire the securities.  Seller
is acquiring  the Shares for  investment  purposes only for his own account only
and not with a view to, or for resale in  connection  with,  any  "distribution"
thereof  within  the  meaning of the  Securities  Act of 1933,  as amended  (the
"Securities Act").

                  (b)  Seller   understands   that  the  Shares  have  not  been
registered  under the  Securities  Act in  reliance  upon a  specific  exemption
therefrom,  which  exemption  depends upon,  among other  things,  the bona fide
nature of his investment intent as expressed herein. In this connection,  Seller
understands  that, in the view of the  Securities and Exchange  Commission  (the
"SEC"),  the  statutory  basis  for such  exemption  may be  unavailable  if his
representation  was  predicated  solely upon a present  intention  to hold these
Shares for the minimum capital gains period specified under tax statutes,  for a
deferred  sale,  for or until an increase or decrease in the market price of the
securities, or for a period of one year or any other fixed period in the future.

                  (c) Seller  further  understands  that the Shares must be held
indefinitely unless  subsequently  registered under the Securities Act or unless
an  exemption  from  registration  is  otherwise  available.   Moreover,  Seller
understands  that the Company is under no obligation to register the Shares.  In
addition,  Seller understands that the certificate evidencing the Shares will be
imprinted with a legend which  prohibits the transfer of such Shares unless they
are  registered or such  registration  is not required in the opinion of counsel
for the Company.

                  (d) Seller is familiar  with the  provisions  of Rules144  and
701, each promulgated under the Securities Act, which, in substance,  permit the
limited  public  resale  of  "restricted   securities"  acquired,   directly  or
indirectly,  from the issuer thereof (or from an affiliate of such issuer), in a
non-public  offering subject to the satisfaction of certain  conditions.  In the
event  that  the  Company  remains  subject  to the  reporting  requirements  of
Section13 or 15(d) of the Securities  Exchange Act of 1934 (the "Exchange Act"),
any  securities  exempt  under Rule 701 may be resold by the Seller  ninety (90)
days  thereafter,  subject to the  satisfaction  of  certain  of the  conditions
specified by Rule 144,  including  amount other things:  (i) the sale being made
through a broker in an unsolicited  "broker's  transaction"  or in  transactions
directly with a market maker (as said term is defined  under the Exchange  Act);
and  (ii) in the  case of an  affiliate,  the  availability  of  certain  public
information  about the Company,  and the

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                                  Exhibit 10.4

amount of securities  being sold during any three month period not exceeding the
limitations specified in Rule 144(e), if applicable.

If the  Shares  of the  Company  do not  qualify  under  Rule 701 at the time of
       acquisition,  then such  Shares  may be resold by the  Seller in  certain
       limited  circumstances  subject  to the  provisions  of Rule  144,  which
       requires  among other  things:  (i) the  availability  of certain  public
       information  about the Company;  (ii) the resale  occurring not less than
       one year after the Seller has acquired, and made full payment for (within
       the meaning of Rule 144),  the Shares to be sold;  and, in the case of an
       affiliate,  or of a  non-affiliate  who has held the securities less than
       two years,  (iii) the sale being made through a broker in an  unsolicited
       "broker's  transaction" or in  transactions  directly with a market maker
       (as said  term is  defined  under  the  Exchange  Act) and the  amount of
       securities  being sold during any  three-month  period not  exceeding the
       specified limitations stated therein, if applicable.

                  (e) Seller  further  understands  that  while a public  market
currently  exists for shares of the  Company's  common  stock,  the Shares  that
Seller  is  acquiring  pursuant  to the  terms of this  Agreement  have not been
registered under the Securities Act and,  further,  that at the time that Seller
wishes to sell the Shares, there may be no public market upon which to make such
a sale.  Even if such a  public  market  then  exists,  the  Company  may not be
satisfying the current public  information  requirements of Rule 144 or 701, and
that,  in such event,  Seller would be  precluded  from selling the Shares under
Rule 144 or 701 even if the one-year minimum holding period had been satisfied.

                  (f) Seller  further  understands  that in the event all of the
applicable requirements of Rule 144 or 701 are not satisfied, registration under
the Securities Act,  compliance  with  Regulation A, or some other  registration
exemption will be required;  and that,  notwithstanding  the fact that Rules 144
and 701 are not  exclusive,  the Staff of the SEC has expressed its opinion that
persons  proposing  to  sell  private  placement  securities  other  than  in  a
registered  offering and otherwise  than pursuant to Rule 144 or 701 will have a
substantial  burden of proof in establishing that an exemption from registration
is  available  for such  offers  or  sales,  and that  such  persons  and  their
respective brokers who participate in such transactions do so at their own risk.

                  (g) The  address  set  forth  below is the  Seller's  true and
correct  address  of  residence,  and the Seller  has no  present  intention  of
becoming a resident of any other state or jurisdiction.

       10. Legends.  Each certificate or instrument  representing the Shares and
securities  issuable upon conversion thereof will be endorsed with the following
legends:

                  (a)      "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE BEEN
                           ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN
                           CONNECTION WITH THE SALE OR DISTRIBUTION  THEREOF. NO
                           SUCH SALE OR DISPOSITION  MAY BE EFFECTED  WITHOUT AN
                           EFFECTIVE  REGISTRATION  STATE RELATED  THERETO OR AN
                           OPINION  OF  COUNSEL  FOR  THE   COMPANY   THAT  SUCH
                           REGISTRATION IS NOT REQUIRED UNDER THE SECURITIES ACT
                           OF  1933,  AS  AMENDED.   THIS  CERTIFICATE  MUST  BE
                           SURRENDERED TO THE  CORPORATION OR ITS TRANSFER AGENT
                           AS A  CONDITION  PRECEDENT  TO  THE  TRANSFER  OF ANY
                           INTEREST  IN  THE  SECURITIES   REPRESENTED  BY  THIS
                           CERTIFICATE."

                  (b)      Any other legends required by California law or other
                           applicable state blue sky laws.

         11.      General Provisions.

                  (a) Entire  Agreement.  This  Agreement  represents the entire
agreement  and  understanding  between the  Company  and Seller and  supersedes,
merges  and  replaces  any  and  all  prior  oral  and  written  agreements  and
understandings  relating to the  subject  matter of this  Agreement.  Each Party
represents  that it has had the  opportunity to consult with an attorney and has
carefully  read and  understands  the scope and effect of the provisions of this
Agreement.   There  are  no   representations,   agreements,   arrangements   or
understandings,  oral or  written,  among the  Parties  relating  to the subject
matter of this  Agreement  that are not fully  expressed in this  Agreement  and

                                                                     Page 4 of 6
<PAGE>
                                  Exhibit 10.4

neither Party has relied upon any  representation or statement made by the other
Party in entering into this Agreement that is not specifically set forth in this
Agreement.

                  (b)  Modification.  No  modification  of or  amendment to this
Agreement, nor any waiver of any rights under this Agreement, shall be effective
unless in writing and signed by both the Company and Seller.

                  (c)  Authority.  Each of the  Parties  hereto  represents  and
warrants that the  undersigned  has the authority to act on behalf of such Party
and to bind  such  Party  and all who may  claim  through  it to the  terms  and
conditions  of  this  Agreement.  Each of the  Parties  further  represents  and
warrants  that  there are no liens or claims  of lien or  assignments  in law or
equity or otherwise of or against any of the claims or causes of action released
in this Agreement.

                  (d) Execution  and Validity of Agreement.  Each of the Parties
hereto agrees to execute any proper oath or verify any proper document  required
to carry out the terms of this  Agreement.  Each of the  Parties  hereto  hereby
represents and warrants that its  performance of all the terms of this Agreement
will  not  breach  any  other  agreements  to  keep  in  confidence  proprietary
information acquired by it in confidence or in trust from an outside third party
and each of the Parties  further  covenants  and agrees that they will not enter
into, any oral or written agreements in conflict herewith.

                  (e)  Waiver.  No failure or delay by either of the  Parties in
exercising any right,  power or privilege under this Agreement will operate as a
waiver thereof. The waiver by either of the Parties of a breach of any provision
of this  Agreement  will not operate or be construed as a waiver of any other or
subsequent breach.

                  (f)  Severability.  In the event  that any  provision  of this
Agreement  becomes or is declared  by a court of  competent  jurisdiction  to be
illegal, unenforceable or void, the remaining provisions of this Agreement shall
continue in full force and effect  without said  provision and the Parties agree
to amend this Agreement and to substitute and replace such void or unenforceable
provision with a new enforceable  provision  negotiated in good faith which most
nearly effects the Parties original intent upon entering into this Agreement.

                  (g)  Assignment.  Neither of the Parties to this agreement may
assign its rights or delegate  its duties  hereunder  without the prior  written
consent of the other Party.

                  (h)  Successors and Assigns.  This Agreement  shall be binding
upon,  and  inure to the  benefit  of,  the  respective  legal  representatives,
successors and permitted assigns of the Parties.

                  (i)  Notices.  Any  notice  required   or  permitted  by  this
Agreement  shall be in writing and shall be deemed given upon actual  receipt or
(i) upon delivery, if personally  delivered,  (ii) after three days upon deposit
in the mail if sent by prepaid  registered  or certified  mail,  return  receipt
requested,  or (iii)  the next  business  day  after  delivery  to a  commercial
overnight courier service, unless upon appropriate  investigation such courier's
records indicate a latter date. All such notices shall be addressed to the other
Party at the  appropriate  address set forth below or at other such  address for
which such Party has  previously  provided  the other  under the terms of notice
hereunder.

                  (j) Costs. Except as otherwise  specifically  provided herein,
the  Parties  shall each bear their own  costs,  attorneys'  fees and other fees
incurred in connection with the preparation and execution of this Agreement.

                  (k)  Disputes.  In the event of a dispute  between the Parties
arising from or related to this Agreement, the Parties agree that the prevailing
party  in  such  dispute  shall  be  entitled  to  reimbursement  of  reasonable
attorneys' fees and expenses,  in addition to any other rights and remedies that
it may have.

                  (l)  Governing  Law.  This  Agreement  will be governed by and
construed in  accordance  with the laws of the State of  California as such laws
are  applied  to  agreements  entered  into  and  to be  performed  entirely  in
California by California residents.

                                                                     Page 5 of 6
<PAGE>

                                  Exhibit 10.4

                  (m) Consent to Jurisdiction. Each of the Parties hereto hereby
expressly  agrees and consents that the  California  state courts located within
the County of Santa Clara,  California  shall be the exclusive  jurisdiction and
venue in which to  adjudicate  any  dispute  arising  from or  relating  to this
Agreement (unless, if there is exclusive federal  jurisdiction,  then the United
States  District  Court for the  Northern  District of  California  shall be the
exclusive  jurisdiction  and venue for such matters.)  Furthermore,  each of the
Parties hereby  expressly  consents to (i) personal  jurisdiction of the federal
and state courts within California,  (ii) service of process being effected upon
it by  registered  mail sent to the  appropriate  address first set forth at the
beginning  of this  Agreement  or at other such address for which such Party has
previously  provided  under  the  terms  of  notice  hereunder,  and  (iii)  the
uncontested  enforcement  of a final  judgment  from  such  court  in any  other
jurisdiction wherein such Party or any of its assets are present.

                  (n)   Counterparts.   This   Agreement   may  be  executed  in
counterparts, each of which when so executed and delivered shall be deemed to be
an  original,  and all of  which  together  shall  constitute  one and the  same
instrument.

         IN  WITNESS  WHEREOF,  each of the  Parties  hereto  have  caused  this
Assignment  of  Intellectual  Property  and  Transfer of Rights  Agreement to be
executed and delivered as of the Effective Date first set forth above.

COMPANY:                                         SELLER:

SIERRA MONITOR CORPORATION


By:   /S/  Gordon R. Arnold                      By: /S/  Edward Hague
      -----------------------------                  ---------------------------
      Gordon R. Arnold, President                    Edward Hague
      Address:   1991 Tarob Court                    Address: Resident of
                 Milpitas, CA 95035                           California


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