For the longer distances the rates were higher than previously. The rate for the greatest distance within the Prussian postal territory, which under the old rates was 18 silver groschen for a single letter--that is, for a letter up to 3/8 ounce in weight--was now 19 silver groschen. The reduction was greatest for letters going only short distances. The rate for the shortest distances was reduced from 1-1/2 silver groschen to 1 silver groschen. But the higher rates applied to letters passing between the great centres, and these formed the greater part of the whole number. In addition, the progression of the scale of weights was made very rapid. From the earliest days of the Post Office in Prussia the progression of weight had been by the half-ounce, and this had not been changed even in 1766. The scale was now made-- From 3/8 oz. to 1/2 oz. 1-1/2 times the rate " 1/2 " 3/4 " twice the rate " 3/4 " 1 " 2-1/2 times the rate " 1 " 1-1/4 " 3 " " 1-1/4 " 1-1/2 " 3-1/2 " " 1-1/2 " 1-3/4 " 4 " and so on for each quarter-ounce a half rate more.[236] The year 1824 was also noteworthy for the experimental establishment in the district of the Frankfort-on-Oder post office of a rural delivery system. This was the first step towards the general extension of the rural delivery throughout Prussia. The experiment was successful, and the system was extended in the following year. For delivery by the rural letter-carriers an additional charge was made for each letter, according to the following scale:-- For distances not exceeding 1-1/2 miles 1 silver groschen " " " 2 " 2 " " " " 3 " 2-1/2 "