420 



THE POPULAR SCIENCE MONTHLY. 



Xo. 34. On the relation ok tuk Lara- 

 mie MoLLUscAN Fauna to that of tue Slc- 

 ciiEDiNO Fresh-Watkr Eocene and other 

 Groups. By Charles A. White, Pp. 32, 

 with Plates. Price, 10 cents. — xi concep- 

 tioa of the importance of the subject of 

 this treatise is given by the conclusion which 

 the author expresses, that there is a com- 

 plete and unbroken stratigraphical series in 

 the region of his exploration, extending 

 from the Middle Cretaceous to the Upper 

 Eocene, and aggregating nearly or quite two 

 miles in thickness. Yet, while sedimenta- 

 tion was not materially interrupted in a 

 large part of the area, the aqueous life was 

 changed, first from that of a purely marine 

 character to that of alternating bracki.sh 

 and fresh waters, and finally to that of a 

 purely fresh-water character, implying great 

 physical changes without materially inter- 

 rupting sedimentation. The author also 

 observes that in Western Xorth America 

 the fresh-water deposits rival in extent and 

 thickness the great marine formations. Each 

 of the great lacustrine formations described 

 by him has its own distinguishing fauna, 

 the uniform character of which over great 

 areas is quite remarkable. 



Xo. 35. Physical Properties of the 

 Iron Carburets. By Carl Barus and Vin- 

 cent Strouhal. Pp. 62. Price, 10 cents. 

 — This paper embodies reports of studies of 

 the internal structure of tempered steel, and 

 of the color-effects produced by slow oxida- 

 tion of iron carburets. 



No. 36. Subsidence of Fine Solid Par- 

 ticles IN Liquids. By Carl Barus. Pp. 

 54. Price, 10 cents. — The author considers 

 the dependence of the rate of descent upon 

 the figure and physical constants of a single 

 particle, or upon the constants of a stated 

 group of particles ; tries to find some ex- 

 pression for the dependence of subsidence 

 on the molecular conditions of the liquid ; 

 and calls to mind the probability of certain 

 permanent chemical effects of the liquid on 

 the subsiding solid. A second chapter is 

 devoted to the results of experiments upon 

 the dependence of the rate of subsidence on 

 the order of surface, concentration, and tur- 

 bidity. 



No. 37. Types of the Laramie Flora. 

 By Lester F. Ward. Pp. 115, with Fifty- 

 seven Plates. Price, 25 cents, — This is an 



enlargement of the author's " Synopsis of 

 the Flora of the Laramie Group." The 

 plants described and illustrated in it were 

 collected by himself in the seasons of 1881 

 and 1883. The principal additions to the 

 original work consist of descriptions of spe- 

 cies regarded as new, and critical discus- 

 sions contributing to the proper understand- 

 ing of the figures and of the nature of the 

 flora under treatment. 



No. 38. Peridotite of Elliott County, 

 Kentucky. By J. S. Diller. Pp. 31. 

 Price, 5 cents. — This memoir concerns dikes 

 of eruptive rock, determined as peridotite, 

 which have been observed in Elliott County, 

 and which the author has studied in co-op- 

 eration with Professor Crandall, of the Ken- 

 tucky State Geological Survey. It contains 

 a large proportion of olivine, some of it in 

 well-defined crystals, with proportions of 

 pyropc and ilmenite ; is associated with 

 nearly horizontal carboniferous sandstones 

 and shales, from which it differs widely in 

 chemical and mineralogical constitution ; 

 and is of special interest, because it affords 

 an instance that is rare of peridotite being 

 found under such circumstances that its 

 eruptive character can be fully estabhshed, 



X"o. 39. The Upper Beaches and Deltas 

 of the Glacial Lake Agassiz. By War- 

 ren Upham. Pp. 84, Price, 10 cents. — 

 The name of Lake Agassiz is given to the 

 extinct body of water which in Glacial times 

 occupied the basin of the Red River of the 

 North. It is assigned to the closing epoch 

 of the Ice age. The exploration of it was 

 begun by the author in 1879 and continued 

 in 1881 and 1885, first under the State Geo- 

 logical Survey, and in the latter year under 

 the United States Survey. The present re- 

 port covers what was observed in these 

 explorations, which were limited to the 

 prairie regions in Minnesota and Dakota. 



ApER^U DE QUELQUES DimCULTES A VAINCRE 



DANS LA Construction du Canal de Pan- 

 ama. (A View of Some Difficulties to be 

 Overcome in the Construction of the Pan- 

 ama Canal.) V>y Dr. Wolfked Nelson, 

 of Montreal. Paris. Pp.71. Price, 1 

 franc. 



The author resided five years on the 

 Isthmus of Panama, engaged in the prac- 

 tice of medicine, and corresponded with sev- 

 eral newspapers, besides contributing mem- 



