The mayor and any one commissioner shall have the power to call special meetings of the board of commissioners, the object of which shall be submitted to said board in writing, and the call and the object, as well as the action of said board thereon, shall be entered upon the journal by the clerk, and no other business shall be transacted except that mentioned in the call. A written notice of said special meeting shall be served personally upon each member of said board or left at his or her usual place of residence at least two hours before the time of such meeting. The notice shall state the time, place and object of such special meeting, and shall be issued by the city clerk to the chief of police, his or her deputy or a policeman, or other city employee, who shall be required to make such service at once as above provided, and the person serving such notice shall make a return in writing of the serving such notice, showing the manner of such service.