Mass. Gen. Laws ch. 67, § 15: Presiding officer during selection of moderator; oath of office

Section 15. The clerk or, if there is no clerk or if he is absent, one of the assessors or of the standing committee shall preside in the choice of a moderator, after which a clerk may be chosen, either pro tempore or to fill the vacancy. The moderator may administer the oath of office to the clerk, and the clerk to the assessors, treasurer and collector, or said oaths may be administered by a justice of the peace.