At Logan's Narrows we reach the valley that skirts the whole eastern base of the Allegheny mountains. Here it becomes necessary to determine the plan to be adopted to overcome the great barrier that separates us from the West. If it is to be surmounted by a road, with the gradients of the western division, the ascent must commence at this point, and gradually wind its way to the summit, by an almost continuous gradient, along the declivities of the mountains for nearly thirty-two miles, crossing the several streams that issue from it, by high bridges, and cutting through or tunneling their dividing summits. Mr. Schlatter, in his Report to the Canal Commissioners, estimates the cost of grading the road, on this ascent, at $1,496,146, which I consider too low for a line with the gradient he adopted, but with the increased maximum grade found necessary on the western division, and a somewhat lengthened line, it would probably prove sufficient. Upon my first reconnoissance of this portion of the country it occurred to me that its peculiar topographical features were lost sight of in the adoption of this plan of ascent, which seemed to look to the single object of obtaining a line with a particular gradient, without regard to the magnitude of the obstacles to be overcome to procure it; while, by pursuing a course from the Narrows, nearly in a direct line to Sugar Run gap (which we shall hereafter show is the best point to cross the mountain), the line would pass through a beautiful valley over comparatively favorable ground, gradually gaining elevation through its whole course, without exceeding the maximum inclination required on the line below, until it reaches the summit of the valley at Robinson's, a distance of fifteen miles. At this point we attain an elevation of 1,174 feet above tide, leaving but 980 feet to be overcome to reach the height found most suitable for passing the mountain, which is attained by a continuous gradient of 80 feet per mile, encountering no _very_ formidable difficulties. A resort to a gradient of 80 or more feet per mile is by no means an unusual expedient on leading railroads. Upon the Western Railroad, in Massachusetts, their maximum gradient is 83½ feet per mile. On the Baltimore & Ohio Railroad they now have, between the waters of the Patapsco and Potomac, on each side of Parr's ridge, gradients of 82 feet per mile, and from the greater elevation of the Allegheny mountains at the place they must cross, it is to be presumed that their gradients at that point will still be increased to a higher rate. Many other instances might be cited, some running up to 120 feet per mile, but it seems unnecessary to extend the list. Theoretically, the power necessary to overcome a given height is the same at all inclinations of the plane of ascent, but in practice, it is to some extent dependent upon the kind of power to be applied.