In November, 1867, 33 feet, 1272 feet. December, 1867, 22 feet, 1294 feet. January, 1868, 33 feet, 1327 feet. February, 1868, 35 feet, 1362 feet. March, 1868, 34 feet, 1396 feet. April, 1868, 24 feet, 1420 feet. May, 1868, 26 feet, 1446 feet. June, 1868, [3] 21 feet, 1467 feet. July, 1868, (Nitro-Glycerin used) 47 feet, 1514 feet. August, 1868, “ 44 feet, 1558 feet. September, 1868, “ [4] 51 feet, 1609 feet. [3] Preparing for machine drilling. [4] September 1, to 24, 5-6 month. Rate 61 feet per month. “But for the improved methods of working introduced, the advance would have been much less satisfactory than that we are enabled to exhibit above. “Concerning the employment of Nitro-Glycerin and machine drilling at West Shaft, it is hardly necessary to remark that many difficulties are to be encountered in the training of men to a new service and in successfully employing a new description of fuse and explosive. Some remarks upon our experience in blasting with this compound, will be found in a subsequent portion of this report. Continuous use of machine drills was commenced at the West Shaft in the latter part of June, and of Nitro-Glycerin as an explosive in the month of August. Some delays were necessarily experienced at first, but greatly improved progress was shortly attained. Some previous trials of machine drilling had been made earlier in the present year, but without continuous progress, upon which satisfactory estimates of success might be based. The last workings made, including the month of September, up to the time of suspension, about five-sixths of a working month, attained a linear progress of 51 feet, with six drills only. The machinery provided at West Shaft is only sufficient to supply the pneumatic power for the ordinary working of the above number, to which accordingly we have been necessarily confined. The two drill carriages employed are larger than those at East End, and are intended to carry five drills each—in all, ten drills working at the breast of the heading. Assuming, as we may safely, that the rate of progress is proportional to the number of drills employed, ten drills would advance 100 feet per month; and with full power provided and further experience to be acquired by the workmen, this and even greater average rates of monthly progress can be made and maintained. These headings are run at top, i.e., above the excavations hereafter to be made, and of such height, and top outline as to correspond with the roof of the completed tunnel.