Of the whole expense of building a railroad, where the country is to any considerable degree broken, the reduction of the natural surface to the required form for the road, that is, the earthwork, or, otherwise, the excavation and embankment, amounts to from thirty to seventy per cent. of the whole cost. Here, then, is certainly an important element on which the engineer is to show his ability; let us look a little at it, even at the risk of being dry. It is by no means necessary to reduce the natural surface of the country to a level or horizontal line; if it were so, there would be an end to all railroads, except on some of the Western prairies. This was not, however, at first known; indeed, those who were second to understand the matter denied the possibility of moving a locomotive even on a level by applying power to the wheels, because, it was said, the wheels would slip round on the smooth iron rail and the engine remain at rest. But lo! when the experiment was tried, it was found that the wheel not only had sufficient bite or adhesion upon the rail to prevent slipping and give a forward motion to the engine, but that a number of cars might be attached and also moved. This point gained, the objectors advanced a step, but again came to a stand, and said, "If you can move a train on a level, that is all, --you can't go up hill." But trial proved that easy inclines (called grades) could be surmounted,--say, rising ten feet for each mile in length. The objectors take another step, but again put down their heavy square-toed foot, and say, "There! aren't you satisfied? you can go over grades of twenty feet per mile, but no more,--so don't try." And here English engineers stop,--twenty feet being considered a pretty stiff grade. Meanwhile, the American engineers Whistler and Latrobe, the one dealing with the Berkshire mountains in Massachusetts, the other with the Alleghanies in Virginia, find that not only are grades of ten and of twenty feet admissible, but, where Nature requires it, inclines of forty, sixty, eighty, and even one hundred feet per mile,--it being only remembered, the while, that just as the steepness of the grade is augmented, the power must be increased. This discovery, when properly used, is of immense advantage; but in the hands of those who do not understand the nice relation which exists between the mechanical and the financial elements of the question, as governed by the speed and weight of trains, and by the funds at the company's disposal, is very liable to be a great injury to the prospects of a road, or even its ruin.