When, in the division among Senators, and Representatives, of documents printed for the use of Congress there is an apportionment to each or either House in round numbers, the Director of the Government Publishing Office may not deliver the full number so accredited at the Senate Service Department and House of Representatives Publications Distribution Service, but only the largest multiple of the number constituting the full membership of that House, including the Secretary and Sergeant at Arms of the Senate and Clerk and Sergeant at Arms of the House, which is contained in the round numbers thus accredited to that House, so that the number delivered divides evenly and without remainder among the Members of the House to which they are delivered; and the remainder of the documents thus resulting shall be turned over to the Superintendent of Documents, to be distributed by him, first, to public and school libraries for the purpose of completing broken sets; second, to public and school libraries that have not been supplied with any portions of the sets, and, lastly, by sale to other persons; the libraries to be named to him by Senators and Representatives; and in this distribution the Superintendent of Documents, as far as practicable, shall make an equal allowance to each Senator and Representative.