Improvements in the means of communication have naturally had considerable effect on the development of the Post Office. The introduction of the stage-coach in the eighteenth century, and of railways and steamboats in the nineteenth, in turn revolutionized the methods of general transportation. By these improvements the capacity of the Post Office was largely increased, and regularity, rapidity, and increased frequency of service made possible. But such general improvements, while of the utmost importance as regards the capacity and character of the Post Office service, can affect the rates of postage only so far as they affect the cost of transportation of the mails, or, by largely increasing traffic, enable economies of business on a large scale to be secured. The stage-coach cheapened the cost of transportation, but, in England, had no effect on the rates of postage, because at the time of its introduction the charges were of a purely fiscal character, and the benefit of cheaper transportation was not passed on to the users of the Post Office. The effect of the introduction of the railway has, at any rate as regards letter postage, not been much greater. Sir Rowland Hill's reform, which standardized letter postage, was based on the ascertained cost of conveyance of mails by stage-coach.[634] He found the cost of such conveyance too small to be taken into account; and the introduction of the railway could not, of course, improve such a situation.[635] The ordinary light letter, weighing on the average considerably less than an ounce, comprises the overwhelming bulk of Post Office traffic, and the heavier letters occupy a quite subsidiary place. With the growth of Post Office traffic, and the consequent economies resulting from business on a large scale, the profits of the Post Office have gradually increased, but not to such an extent as to admit of the reduction of Sir Rowland Hill's penny rate without destroying the net revenue. Any reduction has been limited to the heavier letters. The penny rate for the ordinary letter, though so moderate, is considerably in excess of the average cost even of long-distance letters.[636] Its maintenance, therefore, depends not on economic, but on general political and financial considerations. The question is, what general considerations shall be allowed to govern the rate? Shall it be fixed on the simple basis of cost and revenue, or shall it be fixed at such a level as to yield a surplus revenue? In other words, is it thought that the general public advantages which would result from a reduction of postage to the cost basis would counterbalance the disadvantages which would result from the loss of public revenue? This question will, of course, be answered in accordance with the varying circumstances in the different countries and at different times.[637]