International postal relations were then regulated on the diplomatic theory of national interest - by conventions between individual countries. Where no treaties existed between countries, there was no official mail service. The aim of treaties was not so much to improve the mail service for the population as to make the foreigner pay the bill. Postal treaties were complex and the rates ridiculously nonuniform and high. A letter mailed in the United States with a foreign destination bore four charges - the American domestic rate, the sea postage for maritime transport, the overland transit rate assessed by each country through which it passed, and the domestic rate collected by the country of destination. For ocean transit there were almost as many different rates as there were steamship companies carrying the mail.
Charges on an item to Vienna varied from fifteen to thirty to forty-two cents per half ounce, depending on whether it passed respectively through Bremen, Hamburg, or some French port. One sending a letter to Australia had a choice of six different routes requiring postage ranging from five cents to $1.02 per half ounce. On the same routes different rates prevailed for open and closed mails.
The scale of progression by which rates advanced in accordance with weight was both diverse and complex. In England and the United States the scale was by the half ounce, in France by the ten grams, in Germany and Austria by the loth, and in Denmark, three fourths of a loth.
Some countries fixed the maximum weight of letters at 250 grams; others recognized no limits. Some restricted the thickness of letters; others the width and length. In Denmark, the maximum thickness was two and five-eights centimeters; in England the maximum length, two feet, the maximum width or thickness, one foot.
The system of accounts in each nation was therefore extremely complex. Accompanying each piece of mail was a letter bill upon which the postmaster was required to enter minute details of accounts. Each country was given credit in all other countries through which an item passed for its portion of the sum prepaid on the item. Since accounts were kept by the standard weight and rate of the creditor country, credit on a single letter might require reckoning by the English ounce, the French gram, or the German loth.