The Saint Louis directory for the years 1854-5 :
Note.

From and after the 30th June, 1851, the mode
of computing the rates upon inland letters-i. e. let-
ters from one office within the United States or Terri-
tories to another, and also upon letters between the
United States and the British North American provin-
ces— is to be as follows, to-wit: Single rate, if not ex-
ceeding half an ounce; double rate, if exceeding half
an ounce, but not exceeding an ounce; treble rate, if
exceeding an ounce; but not exceeding an ounce and a
half; and so on, charging an additional rate for every
additional half ounce or fraction of half an ounce.

The mode of computing rates upon letters to Great
Britain, and to all other foreign countries, the British
North American provinces excepted, will remain as at
present, under the act of 3rd March, 1849, and agreea-
bly to instructions appended to the table of foreign
postages.