Section 99(1) in The Calcutta Improvement Act, 1911
(1)Whenever the [State Government] [Substituted by the Adaptation of Laws Order, 1950.] have approved the repayment of a loan from a sinking fund the Board shall establish such a fund and shall pay into it in every year, until the loan is repaid, a sum so calculated that, if regularly paid throughout the period approved by the [State Government] [Substituted by the Adaptation of Laws Order, 1950.] under section 89, it would, with accumulations in the way of compound interest, be sufficient, after payment of all expenses, to pay off the loan at the end of that period.
