

                                                                     Exhibit 8


                          Form of Tax Opinion Letter



Computational Systems Incorporated
835 Innovation Drive
Knoxville, TN  37932
Attn:  Board of Directors

Emerson Electric Co.
8000 W. Florissant Avenue
St. Louis, MO  63136
Attn:  Board of Directors

Dear Sirs:

      In response to your request, we are furnishing you with our opinion, as
of [Closing Date], as to the federal income tax consequences of the proposed
merger (the "Merger") of Emersub LVII, Inc. ("Sub"), a Delaware corporation
and a wholly-owned subsidiary of Emerson Electric Co. ("Parent"), a Missouri
corporation, with and into Computational Systems, Incorporated (the
"Company"), a Tennessee corporation, pursuant to the statutory merger laws of
the State of Delaware.  For purposes of this opinion, we have relied upon, and
assumed the completeness, truth and accuracy of, the information contained in
the Agreement and Plan of Merger dated as of October 17, 1997, with
attachments thereto, and the Proxy Statement/ Prospectus dated November 24,
1997, without having independently confirmed the accuracy thereof.  The terms
defined in such documents have the same meaning where referenced in this
opinion.  In addition, we have relied upon the letters dated as of [Closing
Date], containing representations of Parent and the Company, and have assumed,
in connection therewith, that any such representations that are qualified by
reference to the knowledge of the representor (e.g., a representation that a
statement is true "to the knowledge of" management) are true without such
qualification.

      Based upon the foregoing, and provided that the facts, assumptions, and
representations referenced above set forth the facts relating to the Merger
fully and accurately as of the date hereof, and will set forth such facts
fully and accurately as of the Effective Time of the Merger, we are of the
opinion that the Merger will constitute a "reorganization" within the meaning
of section 368(a) of the Code, and that Parent, Sub, and the Company will each
be "a party to the reorganization" within the meaning of section 368(b) of the
Code.

      This opinion relates solely to the federal income tax consequences of the
Merger discussed herein, and no opinion is expressed as to the consequences
under any foreign, state or local tax law.  Except as explicitly stated
herein, no other opinion is expressed or implied.  This opinion is based upon
the currently applicable provisions of the Code, regulations thereunder,
current published positions of the Internal Revenue Service and judicial
authorities published to date, all of which are subject to change by the
Congress, the Treasury Department, the Internal Revenue Service or the courts.
Any such change may be retroactive with respect to transactions entered into
prior to the date of such change.  No assurance can be provided as to the
effect upon our opinion of any such change.  Finally, this opinion is not
binding upon the Internal Revenue Service or the courts, and no assurance can
be given that they will accept this opinion or agree with the views expressed
herein.

      This opinion is intended for the sole benefit of Parent, Sub, and the
Company, and is not to be relied upon by any other person without our prior
written consent.


                                    Very truly yours,




