.September 26, 1884.] 



SCIENCE. 



325 



sluices which are automatically opened and shut by- 

 large floats; and the second consists principally of an 

 arm dragging along on the bottom, and taking various 

 angles according to the depth of the river. Prof. 

 J. B. Johnson's paper on Three problems in river 

 physics was devoted to a discussion of the transpor- 

 tation of sediment, and the formation and removal 

 of sandbars; the flow of water in natural channels; 

 and the relation of levees to great floods, and to the 

 low-water navigation of rivers. Sediment was dis- 

 tinguished as either continuously or discontinuously 

 in suspension, or as rolled along the bottom; and the 

 action of the second sort in the formation of bars 

 was discussed. It was also shown, that the third 

 kind produces sand-reefs on the bottom which move 

 along perhaps ten to thirty feet per day: they are 

 sometimes fifteen feet high, and succeed each other 

 at intervals of some three hundred feet. For the 

 flow of water, the old formulae were shown to be 

 worthless ; but the author did not make the mistake 

 of giving new ones. Levees were discussed, and their 

 use discountenanced ; waste weirs into side outlets 

 being recommended. This paper will be printed in 

 full. Mr. O. Smith's paper on topography of ma- 

 chines referred to more exact and systematic meth- 

 ods in drawing and speaking of machines and parts 

 thereof, and should have been discussed on Monday. 

 On Thursday, Mr. Arthur Rigg discussed the advan- 

 tages of trip and eccentric gears, and a somewhat 

 lengthy discussion ensued. It appeared that the 

 American practice of employing simple valve-gearing 

 in small quick-speed engines was approved of, though 

 giving a somewhat inferior card to that of a trip-gear 

 engine. Three other papers — ' The strength of cast 

 iron,' W. J. Millar; 'Experiments on belting,' G. 

 Lanza; 'Steam-engine tests,' C. H. Peabody — were, 

 in the absence of the authors, presented by Professors 

 Wood and Webb ; and the session concluded with an 

 interesting talk by vice-president R. H. Thurston, on 

 the development of the philosophy of heat-engines. 



PROCEEDINGS OF THE SECTION OF 

 GEOLOGY AND GEOGRAPHY. 



It will be readily admitted by all who were in 

 attendance upon any of its proceedings, that the 

 sessions of section E of the Philadelphia meeting of 

 the American association possessed, both as regards 

 the numbers present and the character of the papers 

 presented, a very unusual interest. As a special 

 feature, might perhaps be mentioned the large amount 

 of attention devoted to those most difficult of geo- 

 logical problems relating to prefossiliferous strata 

 and the origin of the crystalline schists, — questions 

 which not only in the meetings of the association, 

 but in the world generally, seem year by year to 

 be claiming an ever-increasing share of geologists' 

 thought and study. 



This tendency was well marked by the opening 

 address of the vice-president of the section, Prof. 

 N. H. Winchell, on the crystalline rocks of the north- 

 west, a paper which needs no notice here, as we have 



already printed an abstract, and which according to 

 the usages of the section admitted of no discussion. 



The real business of the section was commenced 

 on Friday morning, the day succeeding its organiza- 

 tion, by the reading of a paper, by Prof. S. G-. Wil- 

 liams of Cornell university, on the gypsum deposits 

 of Cayuga county, 1ST. Y. He maintained, on paleonto- 

 logical evidence, that these beds were members of the 

 lower Helderberg formation, instead of belonging, as 

 might have been expected, to the Salina period. A 

 section illustrating their occurrence was discussed, 

 and four distinct reasons given for considering their 

 origin to be due to the action of sulphur-springs on 

 beds of impure limestone. 



A paper by Prof. E. Orton of Columbus followed, 

 in which he showed how the remarkable symmetry 

 and order pervading the lower coal measures in west- 

 ern Pennsylvania and Ohio extend across the Ohio 

 River into Kentucky. Sections in both Pennsylvania 

 and Ohio were carefully analyzed, and especial stress 

 laid upon the importance of certain thin limestone 

 beds accompanying the coal measures as reliable geo- 

 logical guides. Credit was given to Professor Cran- 

 dall for having first shown that the sequence of beds 

 was the same on the Kentucky side of the Ohio River 

 as it was in Ohio. An interesting discussion followed 

 this paper, between Professors Lesley and Orton; the 

 former affirming that no traces can now be found of 

 what were the shores of the original coal basin, and 

 that no elevations or depressions accompanied the 

 deposits of coal-seams, while the latter maintained 

 that the evidences of the old shore-line, especially in 

 Ohio, were very manifest. 



Prof. F. D. Chester read an account of the geologi- 

 cal survey of the state of Delaware, upon which he 

 has for some time been engaged. He exhibited an 

 unpublished map defining the small areas occupied 

 by Laurentian and Cambro-silurian rocks in the north- 

 ern part of the state; but naturally devoted most of 

 his attention to the more important clays, sands, and 

 marls, which represent the cretaceous, tertiary, and 

 quaternary formations. 



The vice-president of the section, Professor Win- 

 chell, followed with a description of a salt-well situ- 

 ated at Humboldt, Minn. The brine, although now 

 to be found principally in rocks of Devonian or Silu- 

 rian age, he considers to have originated in overlying 

 strata, probably carboniferous. 



Professor Orton, in a paper on the distribution of 

 petroleum and inflammable gas in Ohio, showed that 

 while scarcely a formation in the whole state was 

 altogether free from them, their presence in really 

 valuable quantities was confined to the subcarbon- 

 iferous, and even here to two members of this series, 

 — the Waverly conglomerate and Berea grit. These 

 strata alone satisfy the necessary conditions of pro- 

 ductive 'oil sands,' i.e., porous layers of sandstone 

 or conglomerate sealed up between impervious layers 

 of shale. As closely connected with the petroleum 

 deposits of Ohio were mentioned the salt-wells, which 

 yield an abundance of brine derived from the same 

 'oil sands.' This brine is remarkable for the amount 

 of bromine it contains, the production here — one 



