96 THE POPULAR SCIENCE MONTHLY. 



of his discoveries — Mather, Emmons, and Vamixem. It has given 

 existence to publications that have become classic (1836 to 1842). 

 By the side of these promoters who have the merit of having been 

 the first to conquer the greatest difficulties, justice demands that 

 there should be written the names of two geologists not attached 

 officially to the service of the United States, whose powerful influ- 

 ence ought to be proclaimed. Our compatriot De Verneuil pur- 

 sued since 1846, with the success that is well known, a task which 

 no other could better undertake, that of comparing upon the two 

 continents all the sedimentary deposits, from the most ancient 

 down to those that contain the coal ; and Dana, by his original 

 work and by his excellent books, has contributed singularly to 

 the education of all those who, in Europe as well as in America, 

 devoted themselves and still devote themselves to the study of 

 geology and mineralogy. 



The first results attained proved the utility of like enterprises. 

 Thus, following the steps of the local governments, the Federal 

 Government entered into the same path. 



It was at first for the great Territories of the West, little 

 known and not yet classed as independent States. The wise 

 geologist Hayden, to whom this study was confided and of whom 

 we deplore the loss, worked there with ardor during a dozen 

 years. First of all had to be adopted a rational plan for an ex- 

 ploration at the same time geographic and geologic. This new 

 service bore, indeed, the title of Geological and Geographical 

 Survey of the Territories. Then followed the discovery in 1871, 

 and the detailed exploration in 1872, of the region of the geysers 

 of the Yellowstone ; from 1873 to 1879 the complete topographic 

 and geologic survey of the Alpine part of the Rocky Mountains 

 comprised in the State of Colorado. The atlas which unites all 

 these researches (1877) is a chef-d'oeuvre of cartography ; it is in 

 great part the work of Mr. Holmes, the artist-geologist, of whom 

 one admires the incomparable sketches scattered in profusion 

 through the official publications. 



In order to explore the Rocky Mountains (1869 to 1875), Mr. 

 J. W. Powell descended by water the celebrated and dangerous 

 canons of the Colorado, and made a report which has become 

 classic on the phenomena of erosion. During the same epoch Mr. 

 Gilbert made an extremely remarkable study of the Henry Moun- 

 tains. 



At the same time the Engineer Department of the United 

 States Army was charged with work of the same class over an 

 immense country still little more than desert and very little 

 known. The title of this new service, " Geological and geographi- 

 cal exploration and survey of the one hundredth meridian," shows 

 that, in this case also, the examination of the constitution of the 



