The retirement benefits and other compensation provided for by this chapter shall be paid out of a retirement fund which shall be made up from the funds available from the following sources:
I. The moneys heretofore or hereafter appropriated by the legislature to carry out the provisions hereof.
II. The moneys received from assessments from firemen as provided in RSA 102:9.
III. The moneys received from assessments from towns, cities or precincts as provided in RSA 102:10.
IV. Any donations made to said fund as provided in RSA 102:11.