OO 
= Ses nn nn oe 
Geology and Mineralogy. 423 
The distances between the junctions were BM =1°9 cm. and MT 
2-0) .¢m. 
K(MB)  64°5+-2°0  32°2 | 
kK(TM)  69°0-+1:9 36°3 
(13.) Thus we see, that for slate, with lines of flux parallel to 
cleavage planes, the mean conductivity in the range from 123° C, 
to 202° C. is 91 per cent of the mean conductivity in the range 
from 50° C. to 123° C., and for granite, the mean conductivity in 
the range from 145° C. to 214° C. is 88 per cent of the mean con- 
ductivity in the range from 81° C. to 145° C. The general plan 
of apparatus, described above, which we have used only for com- 
paring the conductivities at different temperatures, will, we 
believe, be found readily applicable to the determination of con- 
ductivities in absolute measure.— Proc. Roy. Soc., No. 349. 
2. United States Geological Survey: 14th Annual Report for 
1892-93 ; by J. W. Powe nt, Director. Part I, Report of the 
Director, pp. 1-321. Part Il, Accompanying papers, pp. 1-597. 
Plates i-lxxiv, figures 1-75. Washington, 1894.—This report 
of the annual progress of the work of the government survey 
contains more than the usual number of valuable contributions to 
geological science. The following is the list of accompanying 
papers, viz: 
W. J. McGue: Potable waters of Eastern United States. 
A. C. PEAtz: Natural mineral waters of the United States. 
F. H. NEWELL: Results of stream measurement. 
Wuitman Cross: The Laccolitic mountain group of Colorado, Utah, and 
Arizona. 
WALDEMAR LINDGREN: The gold-silver veins of Ophir, California. 
ARTHUR KEITH: Geology of the Catoctin belt. 
J. S. Dinter: Tertiary revolution in the topography of the Pacific Coast. 
H. W. Turner: The rocks of the Sierra Nevada. 
CHARLES D. Watcortr: Pre-Cambrian rocks of the Unkar terrane, grand cafion 
of the Colorado, Arizona; with notes on the petrographic character of the lavas, 
by JoSEPH Paxon IDDINGS. 
T. NELSON Dae: On the structure of the ridge between the Taconic and 
Green Mountain ranges in Vermont; The structure of Monument Mountain in 
Great Barrington, Massachusetts. 
JOSEPH D, WEEKS: The Potomac and Roaring Creek coal fields in West 
Virginia. © 
0°88. 
The first three papers are of general economic value and are 
more or less directly connected with investigation of the hydro- 
graphic conditions of the various regions of the United States. 
Mr. Newell’s paper on stream measurements is the fifth of a series 
of papers on the discharge of rivers, the other four having been 
published in the 10th, 11th, 12th and 13th annual reports; the 
first three of them in the sets of Irrigation survey reports. 
Mr. Cross’s paper is a valuable contribution to the petrography 
of intrusive rocks. ‘‘The object and plan of the discussion,” the 
author defines to be twofold: “On the one hand it is desired to 
establish more clearly than has previously been attempted the 
various phases characteristic of the intrusion of a certain class of 
