July 1 8, 1878] 



NATURE 



315 



place during the last eighty years. On the whole this 

 constancy in the form d'Arrest considers the principal 

 result of all our studies of this object. The changes, 

 which have been remarked, seem all reduced to mere 

 variations in intensity, but such small alterations may 

 greatly change the impression we get on looking at certain 

 parts of the nebula. 



The nebula has of late been well watched at the United 

 States Naval Observatory. Prof. Holden has been hitherto 

 engaged in making micrometric measurements of pro- 

 minent parts of the nebula and noting the order of bright- 

 ness of the various masses. He will even attempt a little 

 photometry with the 26-in. refractor. The stars suspected 

 to be variable by O. Struve, are nightly observed. From a 

 provisory discussion of the observations, Holden alludes 

 to changes of short period, and a preliminary sketch of 

 the central part shows that his discoveries in nebular 

 astronomy are likely to rank with those of Newcomb and 

 Hall in other parts of the science. W. D. 



AMERICAN GEOLOGICAL SURVEYS 



North-western Wyoming and Yellowstone 

 National Park ^ 



TN a former number of Nature (vol. xii. p. 265) 

 ■*■ some account was given of the various indepen- 

 dent surveys in progress among the western territories 

 of the United States. Allusion was then made to the 

 unfortunate want of concert among them which had led 

 to a reduplication of the work, and consequently to a 

 struggle at Washington between the different surveying 

 staffs, one fighting for a continuance of power, another for 

 very existence. By the decision adopted by Congress the 

 Engineer Department retained control only of those sur- 

 veys which might be required for military purposes, while 

 the geographical, geological, and other surveys, carried on 

 for the purpose of exploring new ground and making its 

 features and productions known were to be taken charge 

 of by the Department of the Interior. Such a limitation 

 ought to be sufficient to prevent any future risk of the 

 same tract of country being surveyed twice by different 

 and independent officers. That it was needed became 

 abundantly evident during the time of the contest which 

 was finally settled by Congress. And the present volume 

 furnishes fresh proof of its necessity. 



Early in the year 1873 the Engineer Department 

 organised a surveying party to make a military recon- 

 naissance of the north-west of Wyoming territory lying 

 between the Union Pacific Railroad and the line of the 

 Northern Pacific Railroad in Montana. As this depart- 

 nient had all along been in the habit of employing 

 civilian geologists, naturaUsts, botanists, and other scien- 

 tific observers, Captain Jones, who took command of 

 the expedition, collected a party of nineteen persons, 

 exclusive of a military escort under four officers. This 

 military character which the engineers have given to their 

 reconnaissances, though, perhaps, hardly avoidable, seems 

 with good reason to have been regarded as irritating to 

 the Indians. During the investigation into the question 

 of reduplication of surveys, it was stated by the geologists 

 of the Department of the Interior that they did not wish 

 any escort of soldiers as they were never molested by the 

 Indians, who would have been suspicious of their move- 

 ments had soldiers accompanied them. Captain Jones, 

 indeed, refers to a large war-party of Sioux Indians which 

 came into Big Horn Valley shortly after he and his expe- 

 dition had passed out of it, and he seems to think that he 

 made a lucky escape. But the appearance of so large a 

 body of armed men as he commanded within the lands 

 reserved by treaty to the Indians could hardly fail to 

 awaken their distrust and set them in motion. 



' Report upon the Reconnaissance of North- Western Wyoming, including 

 Yellowstone National Park, made in the summer of 1873, by W. A. Jones, 

 Capt. U.S. Engineers, with Geological Report by Prof. T. B. Comstock. 

 (Washington : Government Printing Office.) 



The country passed over in the route lay across the 

 formidable range of rugged snow-capped mountains 

 which rise round the head-waters of the Yellowstone, 

 By some travellers this lofty barrier had been pronounced 

 to be inaccessible, one picturesque observer declaring 

 that " a bird cannot fly over that without taking a supply 

 of grub along." Once across the watershed the expe- 

 dition descended upon the basin of the Yellowstone^ 

 which had already become famous for its wonderful hot 

 springs, and had been pretty fully described and carefully 

 mapped. Indeed when one remembers how much had 

 already been done in the scientific exploration of North- 

 western Wyoming, one is .tempted to ask whether the 

 elaborate preparations made by Capt. Jones were really 

 needed. Nearly a half of the geological part of the 

 Report is occupied with a description and discussion of 

 the geyser phenomena of the National Park — a very 

 interesting and important subject, but one which had 

 already been largely treated of, and which does not appear 

 to be quite in its proper place in the midst of a military 

 reconnaissance. Dr. Hayden, who had done so much to 

 make known the structure and the wonders of that region, 

 is cited in the report, but not in such a way as to suggest 

 any adequate notion of the relative importance of his 

 labours and those of Capt. Jones's expedition. The most 

 important geographical point established by the latter 

 traveller was the existence of an easily traversible pass 

 through the mountains between the head of Wind River 

 and the sources of the Yellowstone. He named it 

 Togwotee Pass, and found that though it reaches aa 

 elevation of 9,62 1 feet above the sea, the slopes leading to 

 it are so gentle that a railway might be led through it at 

 a reasonable cost. 



Prof. Comstock, who was attached as geologist to the 

 expedition, contributes a series of geological chapters to 

 the Report. They are well written, and show him to be 

 not only a good observer, but one who endeavours to 

 group what he sees round some leading principles in 

 science. In particular he adopts a systematic method of 

 treatment in preference to the order of observation usually 

 followed in such reports. This plan saves his readers at 

 a distance much time and trouble, besides enabling them 

 to grasp the main outlines of his work far more clearly 

 than would be otherwise possible. He begins by giving 

 a general outline of the physical geography of the region, 

 connecting the area examined by the party with the rest 

 of the Rocky Mountain tracts as far as explored by other 

 observers. Availing himself of the previous labours of 

 Hayden, Clarence King, Whitney, and others, he arranges 

 his narrative of the geological history of the region in 

 stratigraphical order, beginning with the most ancient 

 metamorphic or archsean rocks, and leading his readers 

 through the Silurian, Carboniferous, Triassic, Jurassic, 

 Cretaceous, Tertiary, and Post-tertiary systems. In seven, 

 interesting chapters Prof. Comstock discusses the ques- 

 tions in dynamical geology suggested by the work of the 

 expedition. In pointing out the evidences for glacial 

 action in North-western Wyoming, he admits that even 

 the hardest rocks fail to show traces of glacier-striation ; 

 that in all his journey he had only seen two or three faint 

 scratches approaching the nature of a glacial mark, but 

 which might have been made quite recently. He found,, 

 however, on the Wind River plateau long and high ridges 

 composed of huge gramte boulders and immense blocks 

 of Silurian and other rocks, with intervening lakes or 

 ponds, and he no doubt correctly regards these features 

 as glacier-moraines. He finds evidence of enormous 

 erosion in recent geological times, and points out the 

 causes now at work in producing rapid disintegration and 

 removal of rock. Among these he mentions the great 

 altitude of the region allowing of the accumulation of 

 large masses of snow, and of the alternate freezing and 

 thawing of the snow by night and day ; the steepness 

 of the slopes favouring rapid erosion, and the character 

 of the rocks powerfully influencing alike the amount of 



