Postage Regulations Part two 1889

Fourth Class - Merchandies, Samples, Etc. - Mailable matter of the fourth class includes all matter not embraced in the first, second and third classes, which is not in its form or nature liable to destroy, deface or otherwise damage the contents of the mail-bag, or harm the person or any one engaged in the postal service.
All matter of the fourth class is subject to a postage charge at the rate of one cent an ounce or fraction thereof, to be paid by stamps affixed.

Postal Cards - Postal cards are sold at a fixed rate of one and two cents (for foreign) each, in any quantity. Unclaimed postal cards are never returned to the writer. Anything pasted on or attached to a postal card subjects it to a letter postage.

Money Orders - Orders not over $10, 8 cents;
$10 to $15, 10 cents;
$15 to $30, 15 cents;
$30 to $40, 20 cents;
$40 to $50, 25 cents;
$50 to $60, 30 cents;
$60 to $70, 35 cents;
$70 to $80, 40 cents;
$80 to $100, 45 cents.
Postmasters cannot issue more than three orders to the same person in one day, in favor of the same payee, at the same office.

N.B.- Postal orders or notes under five dollars are issued without corresponding advices, and, when duly receipted, are payable at any money order office in the United States, selected by the bearer. The fee is three cents for each order. Postal notes are payable to bearer when presented at office of issue. The government is not liable after a note has once been paid. Postal notes are invalid at expiration of three calendar months from the last day of the month issue.

Foreign Postage- Canada - letters 2 cts.; and 5 cents on all letters to all countries belonging to the "Universal Postal Union" which embraces all parts of Europe, Mexico, Equador, Cuba, Brazil, Japan, Hong Kong, Chili, Peru, Egypt, Hayti, etc. Latter rate is on each 1/2 ounce; printed matter 2 cts. for 2 ozs.

Source Houghtalings Handbook 1889