two thousand cubic yards have already been taken up. the introduction of the diamond drill and the increased use of machinery in all branches of the labor has permitted a great reduction of the working force. A hundred of the workmen were discharged last week. ten feet thick supported by numerous pillars. The length of the extreme gallery is six hundred feet and of the grand tunnel two hundred and twelve feet and a half. There will ultimately be twenty-eight tunnel headings some of which will extend three hundred. and seventy five feet. rougher work has been executed and to perform the opera tions connected with blasting. Of the six drills used two This drill consists of a hollow steel disk an inch and a half ness it is propelled by compressed air at a pressure of sixty pounds per square inch and cuts its way through the hard drill in eight hours through a mass of granite and quartz. By screwing on additional pieces of pipe it can be propelled ally however through the intervention of a new process in blasting it is expedient to continue a tunnel of this charac ter for a long distance thereby effecting a great saving of time. Sand or clay is then rammed into the bore until it is nearly full to act as a recoil block tp the charge and the rock is blasted section by section. occurred. The nitro-glycerin is made into cartridges from eight to fifteen inches in length about an inch in diameter and holding from four to ei ht ounces. They are coated with a glutinous composition which effectually protects ted to it through a wire connecting with an electric battery. Though a large number of cartridges are often discharged in succession with great rapidity they are never fired at once as the vibration in this case might seriously jar the stone roof opening seams for the admission of the water. The explosions are of tremendous force. shattering the rock into fragments of a size convenient for removal. These are piled on cars drawn by mules running on iren tracks which are laid
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