The supreme disadvantage in building up a great monopoly in order to win traffic for a railroad is, of course, that the moment the shipper becomes sufficiently powerful, he can play off one road against another, thus becoming practically master of the situation. Sindbad is soon overwhelmed by the old man of the sea. And the weaker the road financially, the more powerful is the appeal, to which at last even the strongest lines must succumb. The history of the Standard Oil Company during the eighties clearly exemplifies this. The rapid rise of the cattle "eveners" yet earlier, until, as the private refrigerator car companies they controlled the situation, was primarily traceable to the same causes. The late J. W. Midgly[163] gives a forcible illustration in the attempt in 1894 of ninety-five railroads to reduce the mileage allowance paid for use of oil tank cars owned by private companies from three-fourths to one-half cent per mile, loaded and empty. The Union Tank Line promptly replied that it would in that event at once concentrate all its vast tonnage to points north and west of Chicago, upon the single line--presumably the weakest one--which would continue the old rate. This argument was irresistible; and in the old days of unregulated competition was in the nature of things bound to be so. Careful distinction must be made at this point, between personal discrimination and general rate cutting. Rebating,--that is to say, departure from published tariffs,--occurs in both cases. The difference between the two is that in the one case it is special, particular and secret; while in the other it is so general, if not indeed universal, as to be matter of common knowledge. Rebating, in other words, is a common feature of rate wars. But, on the other hand, general harmony in the rate situation by no means implies the absence of personal favoritism. During a wide-open rate war, indeed, the most iniquitous aspect of rebating,--inequality of treatment as between rival shippers,--may be quite absent. All may be getting the same rate, namely a cut rate; although the chances are of course that the bigger the shipper, the more substantial the concessions offered. It is important to keep this distinction clear, especially since the railways have awakened to the losses to themselves attendant upon rate wars.