Froin the New York Commercial Advertlser. It is evident to every observer that railway building in the United States has recuived a check which will reduce the numder of milos constracted during ing the coming very mate rially below the estimates. After the panic of 1857 the coustmctiun of railroads teil otF to a considerable extent, and it was a long time before a steady increase was irmuitained. ïhon the war followed, and that gave another check to the niovemeut, which reached its greateït development in. 1871 and 1872. In 1857 thero were 21.503 miles of railtoad in the United State?. This nnmber ■ r!r..iblud at the end of 18fï9, and is now almost trebled, the railroad mil;age now being 97,104. Last year the miles built reached (5,327, and the year before 7,779. The estímate for this was more than 8,000, and for next year possibly 10,000. The war of tho grangers gave the ürst blow to these happy calculations, and the panic followed to decpon the impression, and to reduce railway building for the reinainder of the century of the national existenceto a minimum. Scores of rejected roads will remain dormant. Scores of extensions will be retarded, and tracklayers will have a vacation. It is estimated that it eosts the labor of 20,000 men, for one year, to build 1,000 miles of railway. Consequently the railway construction of last year required 130,000 men. Assuming that in August and September this grand army of labor was at work, the blight which so suddenly feil upon it must have shrunk its dimensions to that of a mere battalion. Probably not much more than one-quarter of the work in progress in September is now pusned lorward, and every day brings further reduotion, as fast as contractors can arrange matters with railway corporations growing daily less flush with funds. The Daily Bulletin an excellent authority on these matters, thinks that 5,000 miles of road less than last year will be constructed next year, and there must be a corresponding decline in those branches of trade which contribute to the ous requireinents of coustruotion, equiprnent and running. Estimating the cost of building and equipuient at the low rate of $25,000 per mile, here is at once " a reduction of $125,000,000 in the railroad expenditures ot' the country, which will represent the discharge of 150,000 hands from pursuits conneoted, in one way or another, with the railroad interest." The inere diniinution in railway construction alone will withdraw 100,000 men from labor, wliile suspensions in other connected trades and industries will swell the volume of unemployed men to dimensions even grenter than those so carefully calculated by the Bulletin. Iron furnaces are going out of blast on all sides. Locomotivo and car builders have closed their works or reduced both force and time. The iron interest suffers in sympathy with the non-construction of vailways, and so does the lumber interest, which supplies ties, bridge timber, car materials, etc. A hundred industries are immediately affected, and the evil inüuence pervades the whole comraunity.