vil CONTENTS. 
NUMBER LXXXVIII. 
Pi 
ART. oa ae —Surface Geology of Southwest Pennsylvania ; 
2 
xv eb WTEC RNMON (cs. ays ks ok So ees 5 
xX a Driftless Interior of North America; by J. D. 
Ba ee UES ss es eee ee oe ia 50 
XXXVI ~The Ancient Outlet of Great Salt Lake; by G. K. 
Gotnuer: 53s n ba ce ceed oe a eo 256 
XXXVIL—Projection of Microscope Photographs; by J. C. 
Dinar et oes ei oe a ws aa 59 
XXXVIIL. iy Pee Silurian Fossils in Limestone associated 
with Hydromica slates in Pennsylvania; by F. Pri, Jr., 261 
XX XIX.—Influence of Temperature on the ‘Optical Cousomes 
of Glass; by C. 8. Hastings, - - 
XLI.—Intrusive Nature = ~ Triassic finer of New 
gerepy > by Lo iotseeemrs, 3g Sek et 277 
XLIT. eres Unit of "Blcctrical Resistance; by H. A. 
POOWEAWON or ce eke og ae 281 
XLIT. Groll’s H a = the Origin of Solar and Sidereal 
Heat; by D. RWOOR Sos bce as ES ie 291 
XLIV. —Chemieal Composition of Guanajuatite, a Selenide of 
Bismuth from Guanajuato; by J. W. Maier, .__.___- 294 
LV. ge on Solar Victories and Optical Sindics: ; by 
8. RROGIN Serio ey ecient. ce tees 297 
XLVI.—Tree-like Fossil Plant, AL h came in —_— Upper 
Silurian Rocks of Ohio; by E. W. Crave 
poumiinns eee 
Chemistry and Physics.—Fundame: RTHELOT, 304.— 
Data, Br - 
Relations ‘between the ‘Koa: pe of = ce nts, WACHTER: Prepara- 
ion n, GATEHOUSE: Method of separating Crystallize spe- 
from Silicates, LAUFER, 305.—Stannous Chlori the analysis 
of Nitro-compounds, Lue T: Catalytic action of Carbon Disulphide, HELL 
and 306.—Conversion of Nitriles into Amides, PINNER an 
Que a Pentacid Alcohol, Homa Acids o utter, Kinezert, 307 
TT, 
New Class of Acid ge ViLiieRs: Electro-Magnetic and Calorimetric Absolute 
Measur Ek: Chemi ynamies, C. R. A. Wrieut and A. P. 
Lurr, 308. aa For ae? : Haloid ae of Antimony, J. P. Cooks, Jr., 
310.—The Telephone, an Instrument of Pre ion, G. Fo = 12. 
srishatin = Teen Shake of ay ortho R. D. sarees, 313.— 
; 315. 
New Jersey, 316.—First and Second lacial Eras of s with 
flowers from the Coal-region r Pemmepoae : Mineral Caves of Biches 
Peru, H. SEwELt, 317. ~Homilite, 318, 
Botany and Zoology.—Flora o rhea Nae Africa, 318.—Ferns of Nerth America 
_ Fossil Plants of pean Norma 339. -Elias Magnus Fries : Pourage of the Phar- 
7 eras of parestbes 1877, Dawson, 
rederick Hartt: Hagel Sees - * 
. citing pee Geet 
XL.— —Experiments with Floating Magnets s; by A. M YER, 276 
ae 
. Ee . * z ¥ : ss a esha aes ee 
LE Ge RPE ee eR Ee Oe SN, RT, EE Oe en OST TEES OM PRR SRe SOMES 2 eee RE PU LP Lee eT EIN Se er ee TE Ee Ne Stl 
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