[Illustration: CROSS-SECTION FROM BURLINGTON TO PITTSBURGH] This general description harmonizes with the apt figure used by that master mind in railway economics, Albert Fink. Speaking of this situation, he says, "The trunk lines are nothing but great arteries of commerce, like rivers, only with this difference: the rivers never run across each other, the territory from which they draw their supplies is distinct and well defined." Since his time, by reason of coöperative action for a generation, the confusing maze of railway lines has now been reduced to a single comprehensive system. Cross-currents of trade hither and thither have been united or articulated in such a way as, speaking in terms of freight charges, to cause the great internal commerce of the country to flow downhill toward the seaboard in an orderly and reasonable way. The inequalities incident to commercial competition have been modified, or, to revert to our original figure, eroded; so that one may literally speak of the products of the country as flowing, like rivers, in more or less natural channels over the railway lines from the great interior basin towards the Atlantic seaboard. The mathematical precision of the method of computation heretofore described, while theoretically applicable to a series of parallel roads in a flat country, free from either water competition, the competition of cross railway lines, or the competition of towns and cities of unequal size and importance, obviously requires modification to suit the actual traffic conditions in this densely populated trunk line territory. The process of adjustment has been gradual and necessarily tentative. Every influence brought to bear has been subversive of systematic arrangement, tending, that is to say, to amend the scheme out of all semblance to mathematical order. After reading volumes of the Proceedings of the Joint Rate Committee, filled with petitions of railways, towns, and individuals for exception to the general rules, one is surprised to find that, after all, the scheme is so well ordered as it is. It has been held true only by rigid adherence to the rule that by the shortest "workable and worked route" no intermediate place shall be charged more than is charged to any point beyond. In other words, the long and short haul principle is consistently observed. Space does not permit a discussion of all of the factors which have tended to modify the original simple scheme. Three alone may be considered as illustrative of the rest. These are: (1) the effect of railway competition at the important junction points; (2) the influence of the independent cross lines of railway; and (3) commercial competition between producing or distributing centres.