§ 90. Commissioner and deputy commissioner of public works. The
commissioner of public works shall be the head of the department of
public works. He shall appoint, to hold office during his pleasure, a
deputy and such other subordinates as may be prescribed by the board of
estimate and apportionment. In case of the absence or disability of the
commissioner or of a vacancy in the office, the deputy commissioner
shall discharge the duties of the office until the commissioner returns,
his disability ceases or the vacancy is filled. The commissioner and
deputy commissioner before entering upon the discharge of the duties of
their respective offices shall each execute and file with the city clerk
an official undertaking in such penal sum as may be prescribed by the
common council.