From the adoption of compulsory prepayment up to 1879, various regulations had been made from time to time regarding insufficiently paid letters, in order to relieve the Dead Letter Office as far as possible, and yet enforce the prepayment of all mail matter. Nevertheless mistakes continued to be made and the practice of forwarding all letters upon which one full rate was paid, and collecting the balance of the receiver had finally been adopted, the amount to be collected being written or stamped upon the letter. From this practice abuses arose, and by the Act of the XLV Congress, Section III, Chapter 180, Section 26, approved March 3d, 1879, it was enacted: "That all mail matter of the first class upon which one full rate of postage has been prepaid shall be forwarded to its destination charged with the unpaid rate, to be collected on delivery, but postmasters before delivering the same, or any article of mail matter upon which prepayment in full has not been made, shall affix, or cause to be affixed, and cancelled as ordinary stamps are cancelled, one or more stamps equivalent in value to the amount of postage due on such article of mail matter, which stamps shall be of such special design as the Postmaster General shall prescribe, and which shall in no case be sold by any postmaster or received by him in prepayment of postage," etc. Sec. 27. "That any postmaster or other person engaged in the postal service who shall collect and fail to account for the postage due upon any article of mail matter which he may deliver without having previously affixed and cancelled such stamp as herein before provided shall be deemed guilty of a misdemeanor, and on conviction thereof shall be punished by a fine of fifty dollars." Shortly after the passage of this Act the following circular was addressed to all postmasters: Form No. 3288. SPECIAL STAMP FOR POSTAGE DUE. POST OFFICE DEPARTMENT, Office of the Third Assistant Postmaster General, Division of Stamps, Stamped Envelopes and Postal Cards. _Washington, D. C., May 5th 1879._ By Sections 26 and 27 of the Act of Congress, making appropriations for the service of the Post Office Department for the year ending June 30th, 1880, and for other purposes "approved March 3d, 1879, it is made the duty of postmasters to affix to all mail matter that has arrived at destination without full payment of postage, and before delivery of the same, an amount of stamps equal to the postage due, the stamps to be of such special design as the Postmaster General may direct."