The progress made at the West Shaft on the East heading the present year, ending December 31, 1866, is 626 feet and 8 inches. This progress was somewhat lessened by the influx of water in December. The monthly advance has been 52 feet and 2 inches. The average of the eleven months ending with November is 53 feet and 6 inches. Assuming the progress made with glycerine during the three days of its use to be obtainable throughout the year, the monthly progress, using that material, would be 120 feet and 10 inches, on a calculation of twenty-five days to a month, which would give an annual advance of 1,450 feet. Without vouching for results so favorable to the progress of the work, it is impossible to overlook the importance of the experiment; and the Committee are of opinion that this material, if it can be procured, should be introduced into the tunnel and shafts, and a thorough experiment made, in order to determine whether it can be used with an advantage even approximating to that shown by the first trial. Experience has proved that the rock at the Hoosac Mountain is of a peculiar character: comparatively easy to drill, but extremely hard to displace, and that its advantageous excavation requires a strong explosive agent. The difference in the use of weak and strong powder is at once observed, and the effect of simultaneous blasting, by the aid of electricity, is proved by the increased progress of the work since it has been used. It would seem evident, then, without the aid of experiment, that an explosive agent, possessing eight times the power of common powder, would be a valuable auxiliary to this undertaking; and that if such an one could be obtained, and safely used, no time should be lost in procuring a supply. The use of nitro-glycerine in England is not uncommon; its components are well known; and the Committee are informed that it might be advantageously manufactured at any point where it is used. ELECTRICAL FIRING. The experiment of simultaneous blasting by electricity has been made with admitted success. The increased progress in the Central Shaft from an average of about 18-1/2 to 23 feet per month, demonstrates its utility, and will undoubtedly insure the continuance of that mode of firing in preference to the method formerly practised. THE TROY AND GREENFIELD RAILROAD. The completion of the railroad from Greenfield to the tunnel has been contracted for with B. N. Farren, for the sum of $545,000, exclusive of the cost of depot buildings, turn-tables, and engineering expenses. The road to be opened for travel to Shelburne Falls by the 15th of November, 1867, and to the tunnel by the 15th of July, 1868. A lease of the same has been executed to the Fitchburg and the Vermont and Massachusetts Railroad Companies, at a rent of $30,000 per year, to expire on the completion of the tunnel, or whenever the work on the same shall be stopped, by competent authority.