Section 74(3)(f) in The Mumbai Municipal Corporation Act, 1888
(f)the corporation may, in their discretion, appoint a person probationally, for a limited period only, to [any] [The word 'any' was substituted for the word 'either' by Bombay 2 of 1911, Section 2(c).] of the said offices, previous to appointing him for the full term of five years;