EXHIBIT 4.10



                             CELERITY SYSTEMS, INC.
                            9051 EXECUTIVE PARK DRIVE
                                    SUITE 302
                           KNOXVILLE, TENNESSEE 37923

                                                July 11, 1997

Dr. Fenton Scruggs
c/o Celerity Systems, Inc.
9051 Executive Park Drive
Suite 302
Knoxville, Tennessee 37923

Dear Mr. Scruggs:

      We have agreed to purchase, and you have agreed to sell to us, 200,000
shares (the "Shares") of the common stock, $.001 par value per share ("Common
Stock"), of Celerity Systems, Inc., a Tennessee corporation (the "Company"),
owned by you for $.20 per share. Such transaction is being consummated in part,
to enable the Company to obtain additional financing. The Company is
contemplating a financing (the "Bridge Financing"), consisting of the sale of
notes and warrants, to be followed by a public offering of Common Stock.

      This is to confirm the agreement between us concerning the purchase and
sale of the Shares.

      1. Sale and Purchase of the Shares.

            (a) The Company will give you at least 24 hours notice of the
closing of the Bridge Financing. Concurrently with the closing of the Bridge
Financing, in accordance with the terms and conditions hereof and for the
consideration set forth herein, you shall sell, transfer, convey and assign to
the Company and the Company shall purchase from you, all of your right, title
and interest in the Shares;

            (b) Concurrently with the closing of the Bridge Financing, against
delivery of the consideration provided for in subparagraph 1(c) below, you shall
deliver to the Company a stock certificate, or certificates, representing the
Shares duly endorsed in blank, or with stock powers annexed thereto duly
executed in blank, in proper form for transfer of the Shares to the Company upon
delivery;


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            (c) Concurrently with the closing of the Bridge Financing, as
payment in full for the Shares, the Company shall deliver to you a check for
$40,000.

      2. Representations and Warranties. In order to induce the Company to enter
into this Agreement and to purchase the Shares, you make the following
representations and warranties as of the date hereof, which representations and
warranties shall be true and correct as of the closing of the Bridge Financing
and shall survive the execution and delivery of this Agreement and the delivery
of the Shares at the closing of the Bridge Financing:

            (a) The Shares are fully paid and nonassessable, and are owned by
you free and clear of any liens, claims or encumbrances of any kind; and

            (b) There are no existing agreements, options, calls, commitments,
trusts, voting or otherwise, or any rights of any kind whatsoever, granting to
any person or entity, any interest in or rights as to, any of the Shares, or the
right to purchase any Common Stock from you at any time or upon the happening of
any event.

            (c) You acknowledge that you have been advised that the Company is
currently contemplating, and has had discussions with an investment banking firm
as to, a public offering of Common Stock expected to be at $7.50 per share
(after giving effect to a reverse split).

            (d) By virtue of your position, you acknowledge you have access to
the same information as to the Company as would be in a Registration Statement
under the Securities Act of 1933.

      3. This Agreement shall be construed by and interpreted and enforced in
accordance with the laws of the State of New York as applied to contracts made
and fully performed in such state. No modification or waiver of any of the terms
of this Agreement shall be effective unless in writing and signed by all parties
hereto.

      4. This Agreement is the entire agreement between us and supersedes any
other agreement oral or written between us relating to the same subject matter.

      5. This Agreement shall be null and void and of no further force or effect
if the closing of the Bridge Financing has not occurred by September 1, 1997.


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            If the foregoing correctly sets forth our agreement, please so
indicate in the space provided below for that purpose, whereupon this letter
shall constitute a binding agreement between us.

                                       Very truly yours,



                                       /s/ Kenneth D. Van Meter
                                       ---------------------------------
                                       Kenneth D. Van Meter,
                                       Chief Executive Officer

Accepted and Agreed to
this 11th day of July 1997



/s/ Dr. Fenton Scruggs
- ---------------------------
Dr. Fenton Scruggs


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