42. (1) There shall be charged in respect of the duties of the Administrator General such fees, whether by way of percentage or otherwise, as may be prescribed by the Government: ¹[* * *](2) The fees under this section may be at different rates for different estates or classes of estates or for different duties, and shall, so far as may be, be arranged so as to produce an amount sufficient to discharge the salaries and all other expenses incidental to the working of this Act (including such sum as Government may determine to be required to insure the revenues of the Government against loss under this Act).