In the practical application of these truths, however, so many complicated details are involved that there is ample reason for the widest differences of opinion. To decide intelligently upon these practical methods demands special knowledge, in order that all necessary details may be provided for, and rare practical judgment to adapt the method to the means at hand. The investigations which the author has pursued in the preparation of the preceding chapters and for certain other purposes have suggested to him certain principles in the practical execution of plans for the control of various monopolies, which seem to him necessary to success in the work. Well understanding the fallibility of any one man's judgment, especially in these matters of detail, he has determined to outline in a brief way what seem to him the most feasible plans for the control of each class of monopolies. These suggestions, however, are to be regarded in an entirely different light from the general laws propounded in the preceding chapters; and they are presented with a full knowledge of the fact that slight variations in circumstances may necessitate wide changes in plans and processes. Taking up the monopolies which by their use of natural agents or their exercise of a franchise granted by the public, are already acknowledged to be subject to the public control, let us consider first the railway system. The two years in which the Interstate Commerce law has been in force have seen a great progress toward the final solution of this problem, even though railway affairs are at present in so unsatisfactory a condition. The important features of our future policy which now seem to be quite generally understood are: full State and national control over both tariff rates and facilities; the abolition of competition, either by consolidation or by legalized agreements to that end; and strict prohibition of the construction of parallel lines not warranted by the traffic.