Full power is vested in the Secretary of the Interior to provide, in all leases to be executed against any combination among lessees or their assigns, as to ownership, prices, or accommodations at any bathhouse; as well as to make all needful rules and regulations as to the use of the hot water, and to prevent its waste, including full power to authorize the superintendent of said park to make examination and inspection at any time of the manner of using the hot water at any bathtub, that it may be used in proper quantity only, and to prevent its waste; and also full power to provide and fix reasonable maximum charges for all baths, or bathing privileges, or services of any person connected with any bathhouse furnished to bathers; and for reasonable maximum charges to guests at the Arlington Hotel; and also, generally, the Secretary of the Interior may make all necessary rules and regulations as to said bathhouses and the service therein as shall be deemed best for the public interest, and to provide penalties for the violation of any regulation which may be enforced as though provided by Act of Congress. All leases and grants of hot-water privileges shall be held to be subject to all regulations in force on March 3, 1891, or which may be adopted by the Secretary of the Interior, and for any violation of any regulation, known to the proprietor at the time of the offense, the lease or grant may be canceled by the Secretary of the Interior. It shall be expressly provided in all leases and grants of privilege for hot water that the bathhouse for which provision is made shall not be owned or controlled by any person, company, or corporation which may be the owner of or interested (as stockholder or otherwise) in any other bathhouse on or near the Hot Springs National Park; that neither the hot-water privilege granted nor any interest therein, nor the right to operate or control said bathhouse, shall be assigned or transferred by the party of the second part without the approval of the Secretary of the Interior first obtained, in writing; and if the ownership or control of said bathhouse be transferred to any person, company, or corporation owning or interested in any other bathhouse on or near said reservation, the Secretary of the Interior may, for that cause, deprive the bathhouse provided for of the hot water and cancel the lease or agreement. All buildings to be erected in the Hot Springs National Park shall be on plans first approved by the Secretary of the Interior, and shall be required to be fireproof, as nearly as practicable.