The following incident is, to say the least, instructive: during the severe winter of 1867 and 1868, the Deerfield dam became obstructed with ice, and it was important that it should be cleared out without delay; W. P. Granger, Esq., engineer in charge, determined to attempt its removal by a blast of Nitro-Glycerin. In order to appreciate the following details, it must be borne in mind that the current literature of this explosive distinctly asserted that when congealed, the slightest touch or jar was sufficient to explode Nitro-Glycerin. Mr. Granger desired me to prepare for him, ten cartridges, and as he had to carry them in his sleigh from the West end of the Tunnel to the East end or Deerfield dam, a distance of nine miles over the mountain, he requested them to be packed in such a way that they would not be affected by the inclement weather. I therefore caused the Nitro-Glycerin to be warmed up to 90°, warmed the cartridges, and after charging them, packed them in a box with sawdust that had been heated to the same temperature; the box was tied to the back of the sleigh, with a buffalo robe thrown over it; in floundering across the divide where banks, road, hedge and water courses were indistinguishable beneath the drifted snow; horse, sleigh and driver were upset, the box of cartridges got loose, and were spread indiscriminately over the snow; after rectifying this mishap, picking up the various contents of sleigh, and getting ready to start again, it occurred to Mr. Granger to examine his cartridges; his feelings may be imagined when he discovered the Nitro-Glycerin frozen solid; to have left them behind and proceeded to the dam where miners, engineers and laborers were waiting to use this then much dreaded explosive, would never do, so accepting the situation he replaced them in the case, and laying it between his feet proceeded on his way, thinking a heap but saying nothing; arrived, he forthwith attached fuse, exploder, powder and some gun cotton, and inserted the cartridge in the ice; lighting the fuse he retired to a proper distance to watch the explosion; presently a sharp crack indicated that the fuse had done its work, and on proceeding to the hole drilled in the ice, it was found that fragments of the copper cap were imbedded in the solid cylinder of congealed Nitro-Glycerin, which was driven through and out of the tin cartridge into the anchor ice beneath, but not exploded. A second attempt was attended with like results. Foiled in attempting to explode the frozen Nitro-Glycerin, Mr. Granger thawed the contents of another cartridge, attached the fuse and exploder as before; this time the explosion was entirely successful. From that day I have never transported Nitro-Glycerin except in a frozen condition, and to that lesson are we indebted for the safe transmission of more than one hundred and fifty thousand pounds of this explosive, over the roughest roads of New Hampshire, Vermont,