SECT. 10. Said board of trustees is hereby authorized and directed to lease in perpetuity, or for such term of years as the governor and council may approve, the franchises and property, and thereafter to maintain, improve and, operate the railroad, with its branches, of the Vermont and Massachusetts Railroad Company, on the terms following: twenty-five per cent. of the gross earnings of said leased railroad and property shall be reserved annually by said board of trustees as a specific fund out of which they shall pay to said company, first, a sum sufficient to pay the interest on the indebtedness of said company, at the date of said lease, as said interest becomes due, and, second, a yearly rental equal to ten per cent. on the present capital stock of said company, free of all taxes upon the stockholders or said company (and on any additional stock, when the same shall be issued for existing convertible bonds), or such a proportion of said rental, not exceeding said ten per cent. and said taxes as said reserved fund shall be sufficient to pay: _provided_, _however_, that in no year shall there be paid to said company a rental of less than four per cent. on said capital stock, and said taxes together with the amount of said interest; and to the payment of such minimum rental and interest said board of trustees is authorized to pledge the faith of the Commonwealth. Said board of trustees is also authorized to assume and make provision in said lease for the payment of the principal of said indebtedness. The surplus of said reserved fund shall be annually passed by said board of trustees to the account of earnings. When said lease shall have been executed, and while the same continues in force, said Vermont and Massachusetts Railroad Company may elect, from time to time, for a term not exceeding five years, one trustee, who shall be added to said board of trustees, and, upon being sworn to the faithful performance of his duties, shall become an incorporated member of the State Board of Trustees of the Hoosac Tunnel Railroad; and said company may fill vacancies for the remainder of the term.