United States Statutes at Large/Volume 3/17th Congress/1st Session/Resolution 4
April 26, 1822.
IV. Resolution providing for the security in the transmission of letters, &c., in the public mails.
The Postmaster General to introduce, &c. R. Imlay’s plan of copper cases, &c., to test, &c.
Proviso.Resolved, by the Senate and House of Representatives of the United States of America in Congress assembled, That it shall be the duty of the Postmaster General to introduce, as soon as conveniently may be, on one or more of the most exposed routes, Richard Imlay’s plan of copper cases, secured in iron chests, with inside locks and sliding bars in such a way as to test its efficacy in preventing robberies of the mail: Provided, The extra expense for each mail carriage shall not exceed one hundred and fifty dollars.
Approved, April 26, 1822.