As Nitro-Glycerin has 13 times the explosive power of gunpowder, our readers, who are accustomed to use the latter for blasting, can easily ascertain the percentage of accidents in proportion to the amount used, and so judge for themselves as to the comparative safety of these explosives. Really, whilst using, only two lives have been lost; one man rashly advancing to the charge, although advised to desist, whilst his fuse was burning; the other, on change of shift, after a blast, a cartridge having failed to explode, and the blaster neglecting to examine whether his cartridge had exploded, allowed the new shift to proceed drilling in the same rock, and within one inch of the same spot previously drilled, and where a charged cartridge was contained, when after a few inches of drilling progress, they came on to the concealed cartridge—explosion followed. In the magazine where three were killed, in order to hurry up, after a previous night’s spree, it had become the practice, notwithstanding peremptory warnings, to remove the cover of the stove, and expose the naked can of Nitro-Glycerin to the naked fire, of course, explosion must, as it did, follow this reprehensible folly, and disobedience to orders, resulting in killing three men. I have established Tri-Nitro-Glycerin Factories At North Adams, Massachusetts, ALFRED WALLACE, Foreman; At Maysville, Kentucky, JOHN WALLACE, Superintendent; At Kingston, Province Ontario, Upper Canada, H. H. PRATT, Superintendent; In order to facilitate supply, and make deliveries at least possible cost for freight. GEO. M. MOWBRAY, NORTH ADAMS, MASS. Where orders for Exploders, both electric and tape fuse, gutta-percha insulated leading and connecting wire, of quality very superior to any hitherto made in the United States, should be addressed. Agent in New York City: W. B. TOWNSEND, No. 40 Broadway (Room 39.)