After a laborious geological excursion along M'Clure's Springfield section, for about one hundred miles, I visited Dr. D. Hunt, at Northampton. He observed that you had expressed an opinion, that an attentive examination of all the strata constituting the walls of the artificial avenue or drift at the Southampton mines, would bring facts to knowledge, which might, in some degree, subserve the cause of geological science. I am now at the mouth of the drift, having just completed the labour which you had marked out. I employed two miners to commence with me, at the termination of the drift, which is now extended 800 feet into the hill. We broke off large specimens, at very short intervals, throughout the whole extent of the drift. We arrived at its mouth with almost a boat load of specimens. I kept a memorandum of every thing which occurred, while under ground; and I have now arranged the specimens, before the mouth of the drift, in the same order in which they were situated in the earth. Fatigued as I am, I will make my remarks here, in the field, lest something should hereafter escape me, which is now fresh in my recollection. Beginning with the greatest distance to which the miners have penetrated, I will set down my remarks, in fact, in reversed order. 800 feet. The rock is fine-grained gray granite, traversed by veins, lined with quartz crystals, and mostly filled with calcareous spar, often beautifully crystallized. In the same veins blue and purple fluate of lime and copper pyrites frequently occur. 790 feet. The same fine-grained granite is continued, occasionally traversed by veins lined with crystals of quartz; but containing no other minerals. 774 feet. A narrow vein of sulphuret of lead, with walls lined with crystals of quartz. The fairest cubic crystals are slightly attached to the points of the quartz crystals. Yellowish crystals of carbonate of lime are often interspersed among the lead. Sulphate of barytes occurs here also; sometimes in plates meeting at various angles, and forming chambers lined with minute crystals of quartz. Minute crystals of copper pyrites and a little fluate of lime have been found here; also fine specimens of bitter spar. The walls are very compact, fine-grained granite. 760 feet. Coarse, parti-coloured granite. The felspar is flesh-coloured and white; the quartz often bluish or greenish; the mica silvery, greenish, or purplish. 725 feet. A stratum of gray-wacke slate. Texture less firm than of the same rock at the west of Pittsfield. This stratum is very distinct, and about two feet thick.