998 



SCmNGE. 



[N. S. Vol. V. No. 130. 



Furthermore, we think it not too much to say 

 that the illustrations alone are more than worth 

 the price of the book. Beneath each plate are 

 added essential particulars of the size and colors 

 of the species represented, this being evidently 

 intended to supply, for purposes of identifica- 

 tion, what is lacked by the pictures themselves. 



In a work of such general excellence we are 

 somewhat surprised to notice certain careless 

 statements, as, for instance, that the number of 

 shore birds known is 100, instead of more than 

 250 ; that the species of kingfishers are 108, in- 

 stead of about 200 ; and that those of humming 

 birds are 400, whereas above 500 really exist. 

 These slips are, however, too few and of too 

 little consequence to seriously detract from the 

 value and usefulness of the volume. It is with- 

 out doubt the best guide to the study of birds 

 yet published, in this country at least, and 

 should prove, as surely it will, indispensable to 

 the beginner in ornithology. Furthermore, it 

 can scarcely fail to increase the author's already 

 enviable reputation for the felicitous combi- 

 nation of scientific accuracy with popular de- 

 scription. 



Haeey C. Obbrholser. 



Washington, D. C. 



SCIENTIFIC JOURNALS. 

 AMERICAN JOtTENAL OF SCIENCE. 



The July number opens with a paper by A. 

 de Forest Palmer, Jr., on the pressure coefficient 

 of mercury resistance. The author calls atten- 

 tion to the discrepancy existing between the 

 only determinations of the pressure coefficient 

 previously published, namely, those of Barus, 

 who obtained .00003 for the commercial mer- 

 cury up to 400 atmospheres, and Lenz, who 

 found .0002 for pure mercury between one and 

 sixty atmospheres. In the experiments here 

 described the mercury was carefully purified 

 and distilled in a vacuum, and the pressures 

 were obtained by means of the ' Screw com- 

 pressor ' of Barus, which is capable of indicating 

 pressures up to something over 2,000 atmos- 

 pheres. The Carey Foster method of measur- 

 ing resistance was found most reliable. The re- 

 sults of the experiments are contained in two 

 extended tables, and are further tabulated in a 



special chart. Taking /3 as the increment to 

 unit resistance of one atmosphere increase in 

 pressure, the equation obtained is as follows: 



/? = — .0000332 — 5 X 10 -" « 

 where the last term, owing to its extreme 

 smallness, is probably only approximately ac- 

 curate. This result is very closely that of 

 Barus, and the difference can be accounted for 

 by the slight impurities in the commercial 

 mercury used by him. 



C. R. Eastman describes, with a series of 

 figures, some remarkable Ctenacanthus spines 

 from the Keokuk Limestone. Theo. Holm 

 gives a fifth paper of his Studies in the Cypera- 

 cese, devoted to Fuirena squarrosa Michx. and 

 F. scirpoidea Vahl. It is accompanied by two 

 pages of illustrations. S. L. Penfield, of 

 New Haven, and A. Frenzel, of Freiberg, 

 Saxony, have a paper in which they show that 

 the mineral ohalcostibite (wolfsbergite) is iden- 

 tical with guejarite ; they further give a de- 

 tailed description of the form of the ohalcosti- 

 bite from Huanchaca, Bolivia. 



H. W. Fairbanks has two papers, the first 

 describing a striking case of contact meta- 

 morphism on Black Mountain, of the El Paso 

 range, a spur of the Sierra Nevada Mountains, 

 extending easterly into the Mojave desert. This 

 is illustrated by a figure showing the diabase 

 dike, with a slaty zone adjoining, of hard, firm 

 rock, into which the soft tufa has been baked. 

 The second paper describes the tin deposits at 

 Temescal, southern California. The tin depos- 

 its here lie nearly in the center of a rudely 

 semicircular area of granite about two miles in 

 diameter and connected on the east with the 

 great body of similar rock extending indefinitely 

 in that direction. The sedimentary rocks along 

 the edge of the granite area consist of quartzite, 

 mica schist and conglomerate of unknown age. 

 A part, at least, of the slates and limestones of 

 the Santa Ana range are Carboniferous. The 

 semicircular area of granite and portions of the 

 adjoining porphyry have been fissured in a gen- 

 eral northeast and southwest direction along 

 almost innumerable lines, and a black vein 

 matter deposited. The veins are generally small, 

 varying from one-fourth to a few inches in thick- 

 ness, but in the case of the main tin-bearing 

 vein an enormous size is reached at Cajalco 



