Essential officers and servants.

No essential officer or servant shall- (a) unless he is authorized in that behalf by the terms of his contract, resign his appointment or quit his employment without giving written notice, not less than one month previously, to the authority appointing him, of his intention so to do; or (b) Absent himself from duty otherwise than on leave duly granted and not subsequent cancelled; or (c) neglect or refuse to perform any of the duties or willfully perform them in an inefficient manner.