Page:Popular Science Monthly Volume 15.djvu/318

304 and the important litigation between the Eureka and Richmond has been decided on geological grounds; and yet the public has nowhere received the information which it craves as to how it has happened that so many millions have been made from the Comstock mines (by their managers), and so many lost in the White Pine and Emma. The great bonanzas of the California and Consolidated Virginia have nowhere been fully described. A few geologists know that they are simply disconnected patches of rich ore, such as lie in most fissure veins; but the public at large have either no ideas at all about them, or those that are wide of the truth. So we may search in vain through all mining literature for the simple explanation of the problem involved in the Eureka litigation, and in the ephemeral productiveness of the White Pine and Emma, viz., that these mineral deposits are chambers or galleries formed in limestone beds by atmospheric water carrying carbonic acid, and subsequently occupied with ore deposited from ascending solutions which filled these cavities, just as elsewhere the simple crevices of fissure veins.

If any one can imagine the lead-bearing limestones of Missouri or the honeycombed plateau of central Kentucky broken up by volcanic action, the strata set at high angles, and their irregular cavities filled with mineral solutions issuing through fissures from below, he will get a just view of the nature and origin of these mysterious ore deposits, and a ready explanation of their irregular and superficial character.

If Mr. King could have continued his observations on the Comstock, and had investigated all the mineral deposits discovered along this rich belt, so freely opened by the active exploitation of the last ten years, in the same thorough way that he did the Comstock, he would have made a contribution to American geological literature which would have been of great scientific interest, and of a pecuniary value to mine-owners and mine-buyers to be reckoned in millions.

Vol. V. made its appearance in 1871; it was devoted to Botany, and was prepared by Mr. Sereno Watson, with the assistance of a number of our best botanists, who have made special studies of particular families of plants; as Engelmann of the Cactaceæ, Eaton of the Ferns, Tuckerman of the Lichens, etc. Vol. VI., on Microscopic Petrography, by Professor Ferdinand Zirkel, was published in 1876; Vol. IV., on Paleontology and Ornithology, in 1877; Vol. II., which embraces detailed reports by Messrs. Arnold Hague and S. F. Emmons, on the local geology of the belt of territory surveyed, also appeared in the same year; and, finally, Vol. I., written by Mr. King himself, forming a comprehensive review of the systematic geology of the country covered by his explorations, has only just now left the binder's hands.

The magnificent geological atlas intended to accompany and illustrate the reports of the "Survey of the Fortieth Parallel" was issued in 1876. This will compare favorably with any work of its kind done in the Old World, and at the time of its publication it far excelled