There shall be deducted from every payment of salary hereafter made to each sergeant at arms and court crier three per cent of the amount thereof, then there shall be contributed annually by the county an amount equivalent to three per cent of said sergeant at arms’ and court criers’ salary. In case at any time there shall not be sufficient money in such pension fund to pay such pensions, the board of chosen freeholders of the county shall, from time to time, include in any tax levy a sum sufficient to meet the requirements of such pension fund.