POWER OF ATTORNEY

             KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
        appears below constitutes and appoints John J. Hoey or C.B. McDaniel,
        his or her true and lawful attorneys-in-fact and agents, each acting
        alone, with full powers of substitution and resubstitution, for him or
        her and in his or her name, place and stead, in any and all capacities,
        to sign any and all amendments to the Registration Statement on Form S-3
        to which this Power of Attorney is being filed as an Exhibit, including
        post-effective amendments, and to file the same, with all exhibits
        thereto, and other documents in connection therewith, with the
        Securities and Exchange Commission, granting unto said attorney-in-fact
        and agents, full power and authority to do and perform each and every
        act and thing requisite and necessary to be done in and about the
        premises, as fully to all intents and purposes as he or she might or
        could do in person, and hereby ratifies and confirms all that his or her
        said attorneys-in-fact and agents, each acting alone, or his or her
        substitute or substitutes may lawfully do or cause to be done by virtue
        thereof.
                                                            Date
                                                       ------------


        /s/ Dieter Bock                                 May 9, 1995
        ---------------------------------------          
        DIETER BOCK


        /s/ John J. Hoey                                May 9, 1995
        ---------------------------------------
        JOHN J. HOEY

         
        /s/ C.B. McDaniel
        ---------------------------------------         May 9, 1995  
        C.B. MCDANIEL


        /s/ Douglas G. McNair
        ---------------------------------------         May 9, 1995
        DOUGLAS G. MCNAIR


        /s/ John F. Price
        ---------------------------------------         May 9, 1995
        JOHN F. PRICE


        /s/ Robert K. Steer
        ---------------------------------------         May 9, 1995
        ROBERT K. STEER


        /s/ R.E. Whitten
        ---------------------------------------         May 9, 1995
        R. E. WHITTEN