Geology and Natural History. 339 



between the temperature and. light and its electrical conductivity. 

 This is a subject to which much attention has been given in the 

 last decade, and numerous applications in the arts have been 

 found, the most important of which are the light telephone and 

 electrical tele-photography. These technical uses of selenium are 

 well described and illustrated. 



1 1 . Physics for Secondary Schools ; by Charles F. Adams. 

 Pp. 490. New York, 1908 (American Book Co.). Elements of 

 Physics ; by George A. Hoadley. Pp. 464. New York, 1908 

 (American Book Co.). — The above are new text-books, alike in 

 their design to meet the requirements of College Entrance Boards 

 and the various State and Association reports. They are interest- 

 ingly written, are well illustrated and contain a large number of 

 problems. Each contains an Appendix : that of the former 

 including a discussion of variation and proportion, a table of 

 natural sines and tangents and a table of constants for copper 

 wire ; that of the latter, answers to problems and. a summary of 

 the fundamental formula?. d. a. k. 



II. Geology and Natural History. 



1. Iowa Geological Survey, Annual Report for 1907 y 

 Samuel Calvin, State Geologist. Vol. xviii, pp. 386, 16 plates, 

 41 figures. Des Moines, 1908. — The Iowa Surve}^ is continuing 

 its researches in the coal resources of the state and has undertaken 

 investigations of the location, extent, and character of the peat 

 deposits. Arrangements have also been made with the U. S. 

 Geological Survey for cooperation in securing a topographic map 

 for the entire state. In addition to the statistics of mineral 

 production, the report for this year contains an important paper 

 by Charles R. Eastman, on the Devonian Fishes of Iowa, treated 

 under the following heads : Relations of Paleoichthyology to 

 Biology ; Stratigraphy of the Devonian Fish-bearing Beds of 

 Iowa; Evolutionary History of Fishes; Systematic account of 

 Devonian Agnatha and Pisces including the subclasses Elasmo- 

 branchii, Holocephali, Dipneusti, Teleostomi ; Faunal lists. 

 Three maps by Professor Schuchert showing the Devonian 

 paleogeography are included in the illustrations. h. e. g. 



2. Oklahoma Geological Survey ; Chas. N. Gould, Director. 

 Bulletin No. 1, Preliminary Report on the Mineral Resources of 

 Oklahoma; by Chas. N. Gould, L. L. Hutchison and Gaylord 

 Nelson. 80 pp., 11 figs. Norman, 1908. — The recently founded 

 Oklahoma Survey is justifying its existence by a timely study of 

 the economic resources of the state. Among other papers, the 

 first volume includes preliminary reports on coal, oil and gas, 

 asphalt, gypsum, salt, lead and zinc, glass sand, and building- 

 stones, including clay and Portland cement. h. e. g. 



