UNITED STATES
                          SECURITIES AND EXCHANGE COMMISSION
                                Washington, D.C 20549


                                     SCHEDULE 13G


                      Under the Securities Exchange Act of 1934


                                  (Amendment No. 2)*


                                A.O. SMITH CORPORATION
     _________________________________________________________________
                                   (Name of Issuer)

                                    CLASS B COMMON
     _________________________________________________________________
                            (Title of Class of Securities)

                                       83186520
                          __________________________________
                                    (CUSIP Number)


     Check  the following box if a  fee is being paid  with this statement /__/.
     (A  fee is  not required  only if  the filing  person: (1)  has a  previous
     statement on file  reporting beneficial ownership of more than five percent
     of  the class  of securities  described in  Item 1;  and  (2) has  filed no
     amendment  subsequent  thereto  reporting  beneficial  ownership   of  five
     percent or less of such class.) (See Rule 13d-7).

     *The remainder  of this  cover page  shall be  filled out  for a  reporting
     person's initial filing  on this form with respect  to the subject class of
     securities, and for  any subsequent amendment containing  information which
     would alter the disclosures provided in a prior cover page.

     The information required in  the remainder of this cover page shall  not be
     deemed  to be  "filed"  for the  purpose of  Section  18 of  the Securities
     Exchange  Act of  1934 ("Act") or  otherwise subject to  the liabilities of
     that section of  the Act but  shall be subject to  all other provisions  of
     the Act (however, see the Notes).



     SEC 1745 (2/92)              Page 1 of 5 pages







                                                       Page   2   of   5   Pages

     CUSIP No.    83186520               13G
                -------------
      1)      NAME OF REPORTING PERSON
              S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                               Mitchell Hutchins Institutional Investors Inc.
                                                        13-3180862

      2)      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                 (a) /__/
                                                                 (b) /__/
      3)      SEC USE ONLY


      4)      CITIZENSHIP OR PLACE OF ORGANIZATION

                               Delaware

                                       5)       SOLE VOTING POWER
      NUMBER OF
                                                        -0-
       SHARES
                                       6)       SHARED VOTING POWER
     BENEFICIALLY
                                                        1,261,100
       OWNED BY
                                       7)       SOLE DISPOSITIVE POWER
        EACH
                                                        -0-
      REPORTING
                                       8)       SHARED DISPOSITIVE POWER
       PERSON
                                                        1,261,100
        WITH

      9)      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                                                        1,261,100

     10)      CHECK  BOX IF  THE AGGREGATE  AMOUNT IN  ROW (9)  EXCLUDES CERTAIN
              SHARES*


     11)      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                                                        6.03%

     12)      TYPE OF REPORTING PERSON*

                                                        IA

                         *SEE INSTRUCTION BEFORE FILLING OUT!







                                                       Page   3   of   5   Pages

     Item 1.  (a)     Name of Issuer:
                      --------------
                      A.O. Smith Corporation

                      Address of Issuer's Principal Executive Offices:
                      -----------------------------------------------
                      11270 West Park Place
                      Milwaukee, WI  53224-3690


     Item 2.  (a)     Name of Person Filing:
                      ---------------------
                      Mitchell Hutchins Institutional Investors Inc.

              (b)     Address of Principal Business Office:
                      ------------------------------------
                      1285 Avenue of the Americas
                      New York, NY  10019

              (c)     Citizenship:                                      Delaware
                      -----------
              (d)     Title of Class of Securities:               Class B Common
                      ----------------------------
              (e)     CUSIP Number:                                     83186520
                      ------------

     Item 3.  Type of Reporting Person
              ------------------------
              (a)     (  )     Broker or  Dealer registered under  Section 15 of
                               the Act

              (b)     (  )     Bank as defined in Section 3(a)(6)of the Act

              (c)     (  )     Insurance Company as defined in  Section 3(a)(19)
                               of the Act

              (d)     (  )     Investment Company registered under Section  8 of
                               the Investment Company Act

              (e)     (XX)     Investment Adviser Registered  under Section  203
                               of the Investment Advisers Act of 1940







                                                       Page   4   of   5   Pages

              (f)     (  )     Employee Benefit  Plan,  Pension  Fund  which  is
                               subject  to   the  provisions  of  the   Employee
                               Retirement  Income   Security  Act   of  1974  or
                               Endowment Fund; see Section 240.13d-1(b)
                               (1)(ii)(F)

              (g)     (  )     Parent Holding  Company, in  accordance with
                               Section 240.13d-1(b)(ii)(G) (Note:  See Item 7)

              (h)     (  )     Group, in accordance with Section 240.13d-1
                               (b)(1)(ii)(H)


     Item 4.  Ownership:
              ---------
              (a)     Amount Beneficially Owned:                       1,261,100
                      -------------------------
              (b)     Percent of Class:                                    6.03%
                      ----------------
              (c)     Number of Shares as to which such person has:
                      --------------------------------------------
                      (i)      Sole Power to vote or to direct 
                               the vote:                                     -0-

                      (ii)     Shared Power to vote or to direct
                               the vote:                               1,261,100

                      (iii)    Sole Power to dispose or to direct
                               the disposition of:                           -0-

                      (iv)     Shared Power to dispose or to
                               direct the disposition of:              1,261,100


     Item 5.       Ownership of Five Percent or Less of a Class:
                   --------------------------------------------
                   N/A


     Item 6.       Ownership of More than Five Percent on Behalf of Another:
                   --------------------------------------------------------
                   N/A







                                                       Page   5   of   5   Pages

     Item 7.          Identification and Classification of the Subsidiary  Which
                      Acquired  the Security  Being Reported  on  by the  Parent
                      Holding Company:
                      ---------------------------------------------------------
                      N/A


     Item 8.          Identification  and   Classification  of  Members  of  the
                      Group:
                      ---------------------------------------------------
                      N/A


     Item 9.          Notice of Dissolution of Group:
                      ------------------------------
                      N/A


     Item 10.         Certification:
                      -------------
                      By  signing  below I  certify  that,  to  the  best of  my
                      knowledge  and belief,  the securities  referred to  above
                      were acquired in the  ordinary course of business and were
                      not acquired  for  the purpose  of  and  do not  have  the
                      effect  of changing  or  influencing  the control  of  the
                      issuer  of  such  securities  and  were  not  acquired  in
                      connection with  or as  a participant  in any  transaction
                      having such purposes or effect.

                      Signature:
                      ---------
                      After  reasonable inquiry and to the  best of my knowledge
                      and belief,  I certify that  the information set forth  in
                      this statement is true, complete and correct.


                               /s/ William R. Cavell
                      By: ____________________________
                               William R. Cavell
                               Legal Department


                      Date:  February 13, 1995