“Sir: I avail myself of permission to report progress of the arrangement to introduce Nitro-Glycerin for the purpose of blasting in the Hoosac Tunnel, subject to the conditions imposed by you at an interview held in the engineer’s office, during the latter part of October, 1867. These conditions were—
“First. To conduct the operations with a strict regard to the safety of the miners, and to avoid all risks that might endanger the property of the State, connected with the Tunnel.
“Second. The outlay of capital for the necessary works to be defrayed at my own cost and expense.
“Third. That the Nitro-Glycerin should be supplied at current market rates, freight added; the State of Massachusetts furnishing a convenient site for the buildings, compressed air, and a supply of water, free of cost, and to give the subscriber a preference in consideration of his erecting the works adjacent to the Tunnel.
“The reasons that led to this arrangement were, that as the rock found in excavating the Tunnel was exceedingly tough, any increased progress or lineal advance per month without any increased expenditure; in other words, diminished cost per lineal foot and quickened advance, seemed possible only by the use of a more effective explosive agent than gunpowder; that in Nitro-Glycerin this greater power existed, and therefore its use was desirable; the problem being convenience of supply, guarding against the possibility of accident, by planning carefully every detail in its use, rigidly enforcing every precaution, a failure in any of these points involving pecuniary loss in outlay for the works by the party undertaking its supply and superintending its use in the Tunnel.
“Agreeing with you in the propriety of these views, I commenced operations on the 30th of October. During the past two months a convenient two-story factory has been erected, and the necessary apparatus set up therein, about 1000 feet south of the west shaft; within twenty feet of this factory, a small dwelling for myself and an experienced assistant, and about 500 feet further south on the extreme line of land owned by the State, a magazine for storing Nitro-Glycerin has been constructed. Inclement weather somewhat retarded these operations, nevertheless, the crude articles used in the manufacture and every appliance to render the labor of making a “chemically pure” Nitro-Glycerin, without danger to those engaged in its manufacture, were completed and in good working order on the 31st of December, 1867.
“The assistance rendered me by the gentlemen superintending the various departments of the tunnel work, materially contributed to this result, and I gratefully acknowledge their uniform courtesy and promptitude in forwarding my undertaking. Your own constant attendance at the engineer’s office permitted me almost daily to submit my plans, which therefore met no delay in being subjected to the scrutiny of the engineer in charge, who as promptly reported on them.
“On the 2d of January, 1868, I moved up to the works and on the following day tested the apparatus by manufacturing, and although somewhat delayed by the necessity of drying the plastering in the magazine, and introducing suitable heating apparatus to maintain a moderate temperature during this inclement season, (a neglect of which precaution remotely led to the Bergen accident) yet to-day we have a supply of Nitro-Glycerin, properly and safely stored, ready for use. Samples of this have been duly tested for its explosive force by the engineer in charge and his assistant, giving satisfaction as to its tremendous power, and facility of explosion, with a peculiar fuse and exploder. You may therefore rely on a regular supply as needed, and I submit that a month’s consumption be kept on hand, in order that it may free itself from adherent water, which, except other means be used to free it, does not separate for about ten days. Freed from this obstinately adhering moisture, it is safer and more effective for blasting purposes.
“As respects its application to blasting, during the ensuing week the conducting wires will be laid to the east heading (west shaft) and in order to maintain the electrical machine in working order, I have arranged that the act necessary to firing a blast shall be performed in the time-keeper’s office, where the air is dry and therefore favorable to exciting the charge of electricity, but the control and the means to signal for a discharge, will be in the Tunnel at a safe distance from the heading. By this arrangement, although requiring more conducting wire, the incessant repairs to a costly and delicate instrument and disappointment and delay attending miss-fires will be avoided, and the drillers will be detained from their labor at each discharge for a less period of time.
“The order of charging and firing is as follows: When the drill holes have been completed, (say every four hours) signal is made, for the cartridges which are only then taken into the Tunnel, (the Nitro-Glycerin in its containing cartridge in one vessel, the exploders, with priming and connecting wires attached, in another separate vessel.) On arrival at the heading, the miners are dismissed to a safe distance, the drill holes are then gauged, to be assured they will receive the cartridges; now, and for the first time the exploders are attached to the Nitro-Glycerin cartridges, and immediately passed into the drill holes, these latter are plugged with a bung, perforated to allow the delicate connecting wires to pass, (thus avoiding cutting the insulation against the rock, and confining the flame;) connection is made beginning with the return wire to the cartridges consecutively, and on to the conducting wire. The operator now retires from the heading some 300 feet towards the shaft where a simple but important apparatus, or break is arranged; he then and there connects his return wire and his conducting wire to two similar wires that lead to the electrical discharge, which duty is performed in the dry, warm room before referred to, and the explosions take place instantaneously.