Geology and Mineralogy. 55 
tion, the thermo-electric and photo-electric currents Teepeckirely 
generated i in these cases are opposed to each other in direction. 
Phil. Mag., Nov., 1877, p. 330. J. T. 
NKEL concludes from a series of experiments upon the 
photo-electricity of varieties of fluor-spar, that the pes ao phe- 
nomena are largely due to the influence of the chemical rays of 
the spectrum, which cause chemical changes in the eoqatinee ae of 
the crystal. —Ann. der Physik und Chemie, No. 9, 1877, p. 66. 
a eae soe of air at constant pressure and constant vol- 
—li. K R has erence the specific heat of air at con- 
by 
the transverse aes of steel nae excited by a wichopalia 
bow. A 
were compared with those of a tuning fork. H. Kayser conelndss 
from his experiments that the true value of the velocity of sou 
in free air is 332-5 m. The value of &, the specific heat, has been 
— assigned as will be seen from the following table: 
Maso 220 ete 2A ew Cand Biss 25S ee. 1°41 
Weisbach Se Fay ees 74005 ~Rontpér i222 2S its 1°405 
H, Kayser concludes ee the true value is k=1°4106. rah 
alnn., No. 10, 1877, p. 218. 
worescence of the Retina.—M. von Bezold and Dr. hn 
Mag., Nov., 1877, p. 397; Trans. from Berichte d. baier. bane 
Math h. Phys., June, July 7, 1877. 
Il GroLoGgy aND MINERALOGY. 
1. Reports of the United States dtl 8a Surveys west of 
the ‘One-hundredth meridian, in charge of First Lieutenant Guo. 
Wueerer, Corps of Engineers U. 8. Army, under the diree- 
tion of Brig. -Gen. A. A. Humpar nys, Chief of Engineers, U. S. 
Vol. LV. Paleontology; quarto with 83 plates. Washing- 
ton, 1877, Engineer department, U. S. Army.—This large vol- 
ume, a contribution to the science of the country from the 
Wheeler expedition, Bane ae War Department, comprises two 
important memoirs, as foll 
(1.) Report =e the Invertebrate Fossils collected in portions of 
Nevada, Utah, Colorado, New Mexico and Arizona, by pa rties of 
the Expeditions ‘of 1871, 1872, 1873 and 1874; by € Cuar.es A. 
Warre, M.D.: comprising general observations upon the collec- 
tions and the periods they represent; a general view of the classi- 
fication adopted; and descriptions, in successive chapters, of the 
