Decembek 25, 1896.] 



SCIENCE. 



963 



mulated in the depressions of the rugged sur- 

 face ; in most cases this was found to be a 

 coarse granular sand, made up of crystals and 

 angular fragments of quartz, felspar, mica, etc. , 

 sometimes intermixed or superficially coated 

 with finely comminuted and lixiviated material, 

 but more commonly clean. It was impracti- 

 cable to trace the character of the detritus be- 

 low the level of extreme low tide ; but every- 

 thing indicated that examination beneath the 

 waters of the gulf here would reveal consider- 

 able deposits, corresponding at least to the vol- 

 ume of material removed in forming the sea 

 cliffs, which would be found to consist of such 

 material as that observed. It was noted that 

 off the prominent granitic points (six or seven 

 of which were studied) the granitoid sand was 

 coarsest and cleanest, while in the reentrants it 

 was mixed with rounded sand and contained a 

 larger element of comminuted material. The 

 freshly-formed granitic sand differs from ordi- 

 nary arkose, such as that of the Potomac for- 

 mation, only in the more complete decomposi- 

 tion of the felspar and other constituents in 

 the latter. The observations are considered of 

 value as indicating the conditions under which 

 arkose and mixtures of arkose with ordinary 

 sand are produced. 



Mr. Waldemar Lindgren summarized the re- 

 sults of his recent surveys of the mining dis- 

 tricts of Nevada City and Grass Valley, in Cali- 

 fornia, discussing the history of mining opera- 

 tions there, the geology, the mode of origin and 

 character of the fissure systems, the products of 

 vein formation, etc. 



These important districts are situated on the 

 western slope of the Sierra Nevada, in Nevada 

 county, at an elevation of 2, 500 feet, and within 

 them are a great number of important gold de- 

 posits, consisting of quartz veins and gravels. 

 The districts have been worked continuously 

 since 1849. At present the quartz mining in- 

 dustries are by far the more important. The 

 districts are estimated to have produced a total 

 of $113,000,000. 



These districts together form the subject of a 

 folio of the Geologic Atlas of the United States, 

 but just issued from the press, as well as of a 

 treatise, which will be published within a 

 month as a part of the Seventeenth Annual Ee- 



port of the Director of the United States Geolo- 

 gical Survey. W. F. Morsell. 

 U. S. Geological Survey. 



BOSTON SOCIETY OF NATURAL HISTORY. 



The first general meeting of the season was 

 held November 4th, one hundred and seven- 

 teen persons present. 



Prof. George Lincoln Goodale spoke of the 

 reclamation of deserts. The differences be- 

 tween deserts were described and their various 

 aspects noted. The end of Cape Cod was cited 

 as an example of a desert near at hand, and the 

 scanty vegetation of Sable Island and the diflfi- 

 culty of inducing plants to flourish there were 

 mentioned. The distribution of desert plants 

 was noted, and the effects of aridity, the changes 

 brought about by the introduction of water, 

 and the various kinds of water in the soil, were 

 fully described. 



Views of typical deserts in Australia, Africa, 

 and in other parts of the world were shown, 

 Prof. Goodale concluding with an account of 

 the effects of irrigation and of some of the prac- 

 tical difiiculties arising therefrom. 



Samuel Henshaw, 



Secretary. 



THE academy OP SCIENCE OF ST. LOUIS. 



At the meeting of the Academy of Science of 

 St. Louis on the 7th of December, 1896, Prof. 

 H. S. Pritchett presented a paper giving the 

 results of measures of double stars, mostly close 

 binaries, made with the 12J-inch equatorial of 

 the Glasgow Observatory. These observations, 

 compared with similar ones made by him fifteen 

 years earlier, showed some remarkable changes, 

 particularly in the case of 70 Ophiuchi, in which 

 the companion had described an arc of 102°. 

 Others, as S 2120, showed that the motion of 

 the companion star was independent of the 

 brighter one. The speaker gave a general 

 statement of the method of measuring double 

 stars and the method of determining the appa- 

 rent and true orbits. 



Mr. Wm. H. Roever presented an abstract of 

 a paper on the geometrical properties of lines 

 of force proceeding from electrical systems, in 

 which he showed : 



(a) That the curve representing a line of force 



