Geology and Natural History. 147 



catibnal unions. " As to mathematical scope, the calculus is not 

 used, but, in avoiding it, a summational formula is given, and, so 

 far as may be, established." 



The text is divided into five Parts which deal respectively with 

 the mechanical basis of the subject, hydrostatics, hydrokinetics, 

 pneumatics, and practical applications. A large number of exam- 

 ples and problems (507) are distributed throughout the text and 

 near the end of the volume. Not only are all the numerical 

 answers given but a special section is devoted to solutions and to 

 hints regarding the solutions of the more difficult problems. 

 This is followed by the examination questions set by the Board 

 of Education for the years 1912, 1913, and 1914. Tables of 

 physical and mathematical constants precede the index. 



The subject matter is presented in a clear, accurate, and up to 

 date manner. For illustration, the laws of motion are first formu 

 lated according to Newton and then in the modern, almost unim- 

 peachable phraseology of Mach. The student's interest in the 

 subject is stimulated by numerous practical applications such as 

 Giffard's injector, the pulsometer steam pump, Humphrey's inter- 

 nal-combustion pump, the intensifying accumulator, torpedo com- 

 pressors, Gaede's molecular pump, the Blount door check, the 

 Westinghouse air-brake, etc. The diagrams are large and clear, 

 and the number of typographical errors is small. It is therefore 

 clear that the book has made a very favorable impression on the 

 mind of the writer of this brief notice. h. s. u. 



II. Geology and Natural History. 



1. Triassic Life of the Connecticut Valley ; by Richard 

 S. Lull. Bull. 24, Connecticut Geol. and Nat. Hist. Surv., 1915, 

 pp. 285, 3 maps, 12 pis., 126 figs. — Even though the formations 

 of Triassic age in the Connecticut valley yield but few actual 

 organic remains, yet the abundance of trails and footprints in the 

 muds and sands of this time has deeply interested geologists for 

 nearly a century. Professor Lull in this valuable bulletin brings 

 together all that is known of the fossils of this time in the Con- 

 necticut valley, with the view of presenting them as living things, 

 surrounded by the environment of their time. The thickness of 

 the rock series is at least 10,000 feet and may exceed 13,000 feet. 

 Of plants there are 5 conifers, 4 cycads, 1 equisetum, and 2 or 3 

 ferns ; of animal remains there are 1 insect larva, 2 fresh-water 

 bivalves, 20 species of ganoid fishes in 6 genera, 2 aetosaurs, 2 

 phytosaurs, and 5 dinosaurs ; of invertebrate trails there are 49 

 forms in 27 genera; and of vertebrate footprints the astonishing 

 number of 99 species in 44 genera. 



Among the author's more important conclusions are the follow- 

 ing: 



" The older notions of the submarine or estuarine origin of 

 these rocks have been abandoned on the ground of their contain- 



