158 



SCIEJSCE. 



[Vol. VII., No. 159 



Rock,' and the 1 Czar-liberator's Mountain.' One 

 hundred and fifty photographs and sketches were 

 taken, and a large number of geological and other 

 specimens were collected. The expedition will 

 no doubt have important scientific, and perhaps 

 other results. 



THE U. S. GEOLOGICAL SURVEY. 1 



The plan of this volume is the same as that of 

 its predecessors, comprising, first, the summary 

 report of the director ; second, brief administra- 

 tive reports of the chiefs of divisions on the work 

 accomplished in the several departments of the 

 survey, with brief itineraries of the field-parties ; 

 and, third, the accompanying papers, which make 

 up the main part of the volume, and are the only 

 feature of permanent interest or value. These 

 papers are the monographs or final reports finished 

 during the year. The longer monographs appear 

 here in abstract form only, being, like the more 

 fragmentary bulletins, published separately for the 

 use of specialists. But, although the annual volume 

 is not a perfect resume of the survey, it is wisely 

 designed to present all the results of interest to the 

 general reader. 



The principal feature of Major Powell's sum- 

 mary report for 1882-83 is the preliminary state- 

 ment of the proposed topographical and geological 

 map of the United States, with the accompanying 

 map showing the, for the most part, very limited 

 areas which have been surveyed under the author- 

 ity of the various states and of the general gov- 

 ernment, on a scale suitable for the present pur- 

 pose. The scale adopted for the proposed map is 

 1:250,000, or about four miles to the inch, with 

 contour lines for every twenty -five to two hundred 

 feet, according to the character of the topography. 

 It is proposed to publish this general map in atlas 

 sheets, each being composed of one degree of 

 longitude by one of latitude, in areas bounded by 

 parallels and meridians. 



Although the administrative reports indicate a 

 larger amount of topographic and geologic work 

 than for any previous year, the published results 

 are comparatively meagre, the monographic por- 

 tion of this volume falling decidedly below the 

 average in extent, if not in general interest. The 

 most important paper has only an indirect rela- 

 tion to the geology of the United States. This is 

 Captain Dutton's able memoir on the volcanoes of 

 the Hawaiian Islands. This work was not done 

 at the expense of the survey, nor in anticipation 

 of the annexation of the island kingdom to this 



1 Fourth annual report of the U. S. geological survey to 

 the secretary of the interior (1888-88). By j. W. Powell. 

 Washington, Government, 1884. 8°. 



country, but simply as a preparation for the study 

 of the gigantic lava-flows of the Cascade Range 

 in northern California and Oregon, — a work upon 

 which Captain Dutton has since been engaged. 

 Hence criticism of the survey for extending its 

 operations beyond its legitimate field is forestalled, 

 and the publication of this valuable contribution 

 to our knowledge of the noblest of living vol- 

 canoes will undoubtedly be justified by the light 

 which it will throw upon the volcanic phenomena 

 of our north-western territories ; for, while these 

 are unparalleled among the eruptions of historic 

 times, the evident liquidity and the vast volume 

 of the lava plainly suggest the stupendous flows 

 of Hawaii as the proper preparatory field of the 

 student who would bring to their investigation the 

 best comparisons that modern voleanism affords. 



It is impossible here to do justice to the graphic 

 descriptive chapters, which fully sustain the repu- 

 tation achieved by the author for the bold and 

 discriminating portrayal of geologic phenomena, 

 in his reports on the plateau country and the 

 Grand Canon. But the highly important and 

 original chapter on the volcanic problem may not 

 be disposed of so summarily. Captain Dutton 

 has here gathered together the principal facts and 

 conclusions reached in his study of Mauna Loa 

 and Kilauea, with a view to ascertaining whether 

 they shed any new light upon the dark prob- 

 lem of the volcano. He goes to the root of the 

 matter at once by calling attention to the fact that 

 the volcano is essentially a heat problem, and that 

 the final solution to be sought is an explanation 

 of the origin of this heat and its modes of action. 



The universal postulate that the earth's interior 

 is throughout in a state of incandescence is ac- 

 cepted as a matter of course ; but the question as 

 to whether it is mainly liquid or solid is regarded 

 as still in abeyance, and the determination of this 

 point is not considered essential to the discussion 

 of the volcanic problem. Against the view that 

 the penetration of water to the seat of the internal 

 fires is the cause of volcanic action, two objections 

 are urged. 1°. The access of cold water would 

 cool, and probably solidify, the lava. It might be 

 claimed on the other side, however, that the water 

 must be itself very hot before it reaches the lava, 

 and that aqueo-igneous liquefaction takes place at 

 much lower temperatures than dry fusion. The 

 vaporization of the water would, however, absorb 

 a large amount of heat. 2°. But this last consid- 

 eration is rendered unimportant by the second 

 objection ; viz., that liquid water cannot pass the 

 isogeotherm of 772 Q F. (the temperature of its 

 critical point), and hence must be vaporized long 

 before it reaches the lava. 



That aqueous vapor may penetrate to the reser- 



