All penalties and forfeitures exigible under this Act, and the Acts incorporated wholly or partially herewith, or under any byelaw made in pursuance thereof, may be recovered by an ordinary small-debt action in the [F1name of the library authority or museum and art gallery authority, as the case may be, before either the sheriff or justices exercising jurisdiction in the area of the authority]; and the same shall be payable to the [F2library authority or museum and art gallery authority]and shall, when recovered, be applied by them for the purposes of this Act; and in any prosecution under this Act an excerpt from the books of the [F2library authority or museum and art gallery authority] certified by the . . . F3 proper officer, shall be held equivalent to the books of the [F2library authority or museum and art gallery authority], and all entries in the books of the [F2library authority or museum and art gallery authority] bearing that any book or books mentioned or referred to therein has or have been borrowed by the person complained against shall be taken and received as evidence of the fact, and theonus probandi shall be thrown on the party complained against, and if decree passes against such party, he shall be found liable in costs.