This lake, which is called Igomi, Chigomi, and Gitchigomi, by the Indians, as the term is more or less abbreviated, is remarkable for its extent, its depth, and the purity of its waters. It lies in a basin of trap rocks, with alternations of the granite and sand stone series. No variety of calcareous rock is present,[1] and its waters are consequently free from impregnations from this source. As it is the largest and the purest of the series of lakes it is also the highest in position; its altitude being computed at 640 feet above the Atlantic. Its banks are diversified with mural precipices, with extensive deposits of marine sand, and with beds of mixed detritus. Its immediate margin is loaded with primitive boulders and pebble-stones, alternating with shores of yellow and of iron sand. Several bold mountains of primitive construction, stand near the central parts of its south shores, which are in striking contrast with the ruin-like, walled masses, of horizontal structure, which characterize other parts. Among the detritus of its shores are still occasionally found masses of native copper, which are now referred to the trap formation. Of a body of water so irregular in its shape and imperfectly defined, it may be vague to speak of its superficial area, but this may be assumed to cover 30,000 square miles. It embraces numerous islands, the largest of which are Grand, Royal, and Magdalen islands. It has several noble harbors, bays and inlets, and receives numerous rivers. It abounds with fish, the most noted of which are white-fish, sturgeon, and salmon-trout. But by far the most valuable product of its present commerce, is its furs and peltries. The Indian population of its immediate shores, is not great. Exclusive of bands located on the heads of its rivers, it does not exceed 1006 souls, to which may be added 436 for the American side of the St. Mary’s river. Their trade is conducted by 15 clerks, licensed by the Indian department, employing 70 boatmen, interpreters and runners. Recently a mission has been established on Magdalen Island (_La Pointe_ of the traders,) by the American Board of Foreign Missions, and the gospel began to be preached to the natives. The estimated population which, in a comprehensive view, should be added for the south shores, extending to the borders of the Winnebago and Monomonee lands, and running west, to the Sioux line, is, for the northern curve of Green Bay, 210; heads of the Monomonee and Wisconsin rivers, 342; the Chippewa river and its tributaries, 1376; the St. Croix and its tributaries, 895; Grand Portage, and Rainy Lake, 476; to which latter may perhaps be added, 249, making, with the former estimates, 5000 souls.