The above modification is a necessity to avoid the damaging influence of the moisture in the Tunnel, so disturbing in its effect on the machine. I have only to add, that we have under-way apparatus for coating and re-covering damaged insulated wires, an improvement to insure perfect explosion of the Nitro-Glycerin; the manufacture of Abel’s priming for fuse, the formula having been published by the inventor; matters of comparatively minor importance, but where so many blasts are daily occurring, involving considerable saving in cost and express charges, and securing a better article when made by the individual for his own actual use, than when made simply for sale, all tending to greater safety and certainty in firing the blasts, ameliorations that have already been submitted to and approved by your engineer in charge, who will doubtless speedily report the actual results of blasting operations.
Respectfully,
Geo. M. Mowbray, Operative Chemist.
The following letter from the Engineer in charge to the Commissioners, is interesting, as showing that the Nitro-Glycerin we had made, was superior, and possessed far more valuable properties, than that which had been imported from Hamburg:
North Adams, Feb. 18, 1868.
To the Commissioners of the Troy and Greenfield Railroad and Hoosac Tunnel
Gentlemen:—I have to report that yesterday 4 p. m., we exploded eleven cartridges of Nitro-Glycerin in charges of 1-2 lb. each, in open holes without tamping, with entire success. This experiment was made in the East heading of West Shaft. On approaching the heading, the absence of foul gases and smoke was remarkable, the mass of broken rock lay close to the heading, and there was no appearance of any rock thrown to any distance from the heading. Inquiring of the miners if they experienced any headache, elicited the remark they noticed a pleasant smell, but nothing further. This settles the question of its applicability in a close tunnel. I attribute this freedom from the foul gases which we noticed in our experiments a year since, to the evident purity of this Nitro-Glycerin; it differs greatly from all descriptions of the article, and in appearance from that we imported, being a liquid colorless as water, and free from smell or bubbles. That which we imported was a thick, yellow liquid, quite different in appearance from this. I have requested Mr. Mowbray, who manufactures the Nitro-Glycerin, to take charge of the blasting, and informed him that the Commissioners wish him to assume the responsibility of using the Nitro-Glycerin until further orders, or at least until the system of firing is thoroughly organized among the employees.
I enclose his reply, and approve his suggestions, subject to your instructions.
I am very truly yours,
W. P. Granger, Engineer in charge.