One of the important powers of the mayor is the appointment of officials, though usually the assent of the council is necessary to the validity of most appointments. In recent years there has been a considerable extension of this power in a number of the large cities, where the mayor has been given the absolute power of appointing the heads of the administrative departments. Indeed, the tendency now seems to be in the direction of concentrating larger powers of appointment in his hands as a means of fixing responsibility more definitely. There is also a tendency in the direction of giving him a large power of removal, subject to the provision that the official shall be removed only for good cause and that he shall be given a hearing and an opportunity to answer the charges made against him. Finally, the mayor usually has the power to grant pardons for violations of the ordinances of the city, and this power is sometimes extensively used. Thus during the year 1909 the mayor of Chicago released more than 1,100 offenders who had been committed to prison, or about 10 per cent of the whole number committed. In some cities also he may remit fines that have been paid for violations of city ordinances. =Administrative Departments.=--_Single Commissioner System vs. the Board System._--In every large city there are, in addition to the mayor, a number of departments each charged with the conduct of some particular branch of the city's affairs. They are organized on one of two principles: each is under the control either of a board or of a single commissioner. Each method of organization has its advantages and disadvantages, but experience has shown that the single-headed department is the one best calculated to secure efficiency and responsibility, and it is the one most generally employed. The board system is well adapted to secure deliberation, but not promptness and unity of action nor responsibility, because one member may easily shift the responsibility for an error or blunder upon his colleagues. But for certain branches of administration such as the civil service, park administration, school administration, assessments, and possibly others, the board system has important advantages. _Number of Departments._--The number of these administrative departments varies widely among the different cities of the country. In general we find the following departments: a finance department, a law department, a health department, a fire department, a police department, a department of charities, and a department of public works. In some cities, however, the number of departments is much larger than this. Thus in some we find a street cleaning department, a department of buildings, a sewer department, a department of parks, a department of docks, and so on.