484 



NATURE 



{March 21, 1889 



approved of by a Publication Committee of the Associa- 

 tion." No body of men have any such right to interfere 

 with private enterprise ; and the remedy proposed is 

 wholly unscientific in principle, inasmuch as it would lay 

 a sure foundation for systems of cliquism and popery, 

 whose issue would be fatal to legitimate progress. Others 

 there are who would seek the solution of the difficulty in 

 an occasional substitution of the types chosen for teach- 

 ing, and, in fact, such a change is already premeditated. 

 This proposal cannot fail to meet with general approval, 

 but it does not solve the problem ; for, while no doubt it 

 may, at the outset, insure to the examinee manuals of the 

 better class, it will only prolong the evil day of publication 

 of yet other inferior ones. The fault appears to us to lie 

 not in systems, but in the individual. We are not yet 

 rid of the old delusion that anybody can keep the 

 children quiet. The infant-class is too often entrusted 

 to the care of a novice, and with what results past 

 systems of training have shown. " Qu'est-ce qu'une 

 grande vie ? " wrote de Vigny, with the rejoinder, " Ufte 

 pensde de la jeutiesse exUutee par I' age nitir" No 

 one knows better than the English student that the 

 production of an elementary text-book may constitute a 

 leading feature in a great life. Such a work should be 

 other than a medium in which the author airs his 

 knowledge of fads and phantasies (most of which are 

 sure to be wrong in the end) to the exclusion of fact and 

 common-sense, and we hold its construction to be 

 one of the most arduous of all possible tasks. It is, 

 moreover, one for which a man is not fitted until ripened 

 by long experience and meditation, and to none but the 

 most experienced teacher would we intrust that awakening 

 of the " thought of youth," which, if distorted at the out- 

 set, leads to certain failure. Here, to our thinking, lies 

 the clue to the whole position. The matter is one for 

 individual consideration. Upon the mind of the author 

 of this work there has dawned the pens'ee de la jeunesse; 

 in following it up, he has acted prematurely. Had he 

 kept his ideas well in hand, others would have intersected 

 them in the course of time, as his knowledge of (element- 

 ary) fact increased and as his experience ripened. He 

 has done otherwise, and, in his eagerness for notoriety, 

 has piled up, upon a flimsy foundation of words, a scant 

 superstructure, the materials of which are ill-chosen and 

 defective, and badly put together. G. B. H. 



UNITED STATES GEOLOGICAL SURVEY. 

 Monographs of the United States Geological Survey. 

 Vol. XII. Geology and Mining Industry in Leadville, 

 Colorado. By S. F. Emmons. Pp. 747, with Atlas of 

 35 folio Plates. (Washington Government Printing 

 Office, 1886.) 



'"PHE operations of the United States Geological 

 -«- Survey, under the charge of Mr. S. F. Emmons, in 

 the Leadville mining district, have become known to 

 some extent to many geologists in Europe by personal 

 examination on the ground, and more particularly from the 

 valuable summary of their results which appeared in the 

 Report of the Director of the Survey a few years back. 

 But even those most familiar with the thorough manner in 

 which work is done in the office of Mr. Emmons's division 



at Denver can scarcely have been prepared for the mass 

 of information which is presented to them in the present 

 volume. Although the actual productive area of Lead- 

 ville at the date of the survey was estimated at about one 

 square mile, the study of a considerable part of the adja- 

 cent mountain districts was necessary in order to arrive 

 at any general conclusions likely to be of value for practical 

 purposes in regard to the mineral deposits ; and therefore 

 a district of about 15 to 20 miles of the western or 

 Musquito Range of the Rocky Mountains has been sur- 

 veyed, and mapped in very full detail on a scale of 2 inches 

 to a mile. The interior parts of the mining region 

 proper are treated more minutely on a scale of about 6 

 inches to a mile, and the geology and mine works 

 on the three districts of Iron Hill, Carbonate Hill, and 

 Fryer Hill are given on a scale of i to 1920. 



From the maps and the sections which accompany each 

 set, and which, in accordance with the excellent custom of 

 the founder of the Geological Survey of Great Britain, the 

 late Sir H. De la Beche, are constructed to the same scale 

 both for heights and distances, it appears that the country 

 described consists essentially of a series of ridges and 

 furrows of sedimentary rocks resting upon an Archaean 

 foundation forming the central mass of the Rocky Moun- 

 tains. The most important member of this sedimentary 

 series, the blue or metalliferous limestone, is a blue-gray 

 dolomite of Lower Carboniferous age, which, at or near 

 its contact with an overlying igneous sheet, known as the 

 white or Leadville porphyry, is changed over considerable 

 areas, but in an extremely irregular fashion, into a mass 

 of clay and quartz charged with carbonate and sulphide 

 of lead, chloride and bromide of silver, manganese and 

 iron ores, which are obviously of secondary origin, and 

 derived from the alteration of metallic sulphides. The 

 upper surface of the deposit, being formed by the base of 

 the porphyry sheet, is comparatively regular ; but below, 

 the boundary is exceedingly ill defined, the metalliferous 

 mass — which in the principal mines resembles a brown 

 garden-mould, mottled with dark-coloured patches in 

 places — shading off into the unchanged limestone ; it being, 

 in fact, a pseudomorphous change of the latter rock by 

 infiltration of metalliferous salts from the weathering of the 

 overlying porphyry subsequently to the intrusion of the 

 latter, and before the elevation of the Musquito Range — 

 events which have been placed, as the results of detailed 

 geological study, about the close of the Cretaceous period. 



Since the year 1881, when the present Report was 

 substantially completed, the ores of the Leadville district 

 have changed very considerably, the more tractable car- 

 bonates and chlorides originally met with having given 

 place to unchanged sulphides, with the result of com- 

 plicating the processes of reduction. This circumstance 

 detracts a little from the interest of the last section of 

 the work, which is devoted to a very detailed description 

 of the smelting processes as carried on at and near Lead- 

 ville in 1880. This is due to the labour of M. A. Guyard, 

 of the Ecole des Mines, and for some time an assistant 

 to Messrs. Johnson, Matthey, and Co. Unfortunately, 

 he did not live to see the result of his work in 

 print. Subsequently to the date of the Report, 

 some of the larger smelting establishments were 

 removed to localities closer to the fuel-supplies on 

 the eastern side of the Rocky Mountains, and con- 



