SCIENTIFIC LITERATURE. 



277 



strata for the chronology, and to ascer- 

 tain as far as he can the conditions ex- 

 isting during the deposition of the sev- 

 eral strata or groups of strata. After 

 an account of the growth and progress 

 of stratigraphical geology, the nature of 

 the stratified rocks and the law of su- 

 perposition are discussed; the test of 

 included organisms and the methods 

 of classification are explained, the evi- 

 dences of conditions under which strata 

 were formed, and other theoretical points 

 are considered, and the several geologi- 

 cal systems or periods are enumerated 

 under the English nomenclature. Final- 

 ly, the various estimates of geological 

 time and the bases on which they are 

 made are reviewed. 



The American Book Company pub- 

 lishes as a part of the Eclectic System of 

 Industrial Drawing an excellent man- 

 ual of the Elements of Perspective, by 

 Christine Gordon Sullivan, of the Cin- 

 cinnati public schools. It consists of ex- 

 plicit directions and rules on the gen- 

 eral principles of the art, with appli- 

 cations in Isometric Projection and 

 Oblique Perspective, given in concise 

 form and simple, clear language, amply 

 illustrated, and supplemented by prob- 

 lems, in solving which the rules are made 

 practical. 



A convenient manual on Gas and 

 Petroleum Engines has been prepared 

 by A. G. Elliott from the French of 

 Henry dc Graffigny for Whittaker's 

 Electro-Mechanical Series, in recognition 

 of the interest that has been awakened 

 in the application of such engines to 

 supply the place now occupied by horses 

 in drawing vehicles. One chapter deals 

 exclusively with the theory of the gas 

 engines. Other topics treated of are the 

 history of the gas engine, the descrip- 

 tion of existing gas engines, carbureted 

 air engines, petroleum engines, gas-gen- 

 erating plants, engines for use with poor 

 gases, and the maintenance of gas and 

 oil engines. (The Macmillan Company, 

 75 cents.) 



Laboratory Exercises in Anatomy 

 and Physiology (New York: Henry 

 Holt & Co., 60 cents) have been pre- 

 pared by James Edward Peabody for 

 practical application. The precept is 

 emphasized that the pupil should be 

 led to see that most of the materials re- 

 quired for observation and experiment 



are furnished by the organs and tissues 

 of his own body. Directions which have 

 been found in the author's experience 

 necessary to guide the pupil in his ob- 

 servations and experiments are given 

 at the beginning of each topic. The 

 questions following them contemplate 

 the student's seeking the facts from the 

 material itself, and he is expected to be 

 trained to distinguish observed results 

 from the inferences that may be drawn 

 from them. Some home study is con- 

 templated, the results to be afterward 

 reported in class. The book consists al- 

 most entirely of directions for experi- 

 ments, and is interlined with blank 

 sheets for recording observations. 



Geographical Nature Studies (Amer- 

 ican Book Company) is intended by the 

 author, Frank Owen Payne, to assist 

 the teacher, and by pointing out the re- 

 lations, often unrecognized, between fa- 

 miliar phenomena and home geography 

 to guide the study of the class to defi- 

 nite and practical ends. The lessons are 

 intended to fit the comprehension of the 

 youngest pupils, to promote the culti- 

 vation of habits of accurate observation, 

 and to stimulate a desire for more 

 knowledge and broader views of the 

 world. They lead directly up to the 

 point where the more formal study of 

 geography from a text-book begins. 

 The lessons may be used as reading ex- 

 ercises and for topical recitations, and 

 exercises are introduced which may as- 

 sist the cultivation of the power of cor- 

 rect verbal expression in the statement 

 of facts. The exercises concern weather, 

 animals, physical phenomena, and ob- 

 jects about us, and are very various. 



Impressions of Medusae have been 

 observed on the Jurassic lithographic 

 limestones of Solenhofen, and some 

 " problematic fossils " on the Lower 

 Cambrian rocks of Sweden have been 

 regarded as derived from Medusae. Cer- 

 tain nodules, bearing what looked like 

 fiattened-out starfishes " star-cobbles " 

 they were called have been found 

 among the fossils of the Coosa Valley, 

 Alabama. Director Charles D. Walcott, 

 of the United States Geological Survey, 

 concluded that these also represented 

 Medusae, and began an investigation of 

 them which involved a comparison with 

 the Swedish and Bavarian specimens, 

 and was at last enlarged so as to em- 



