436 Scientific Intelligence. 



feigned total deafness can be readily detected by increasing the 

 air pressure to such an extent that the subject can no longer 

 endure the intense sounds emitted by the siren. 



From the point of view of the physicist the most important 

 conclusion drawn by the author is that " The theory of Helmholtz 

 is insufficient for the explanation of the different kinds of deaf- 

 ness : it seems that the auditory centers, situated in the interior 

 of the brain, have a preponderating importance for the differentia- 

 tion and interpretation of the various vibrations which can influ- 

 ence the ear." 



An interesting corollary is deduced from the fact that the 

 curves corresponding to injuries to the inner ear and to the nerve 

 centers have absolute minima. In one curve, for example, deaf- 

 ness is absolute for a and i, but not for ou, o and e. These curves 

 pertain to cases of deaf-muteness, and the author explains, in the 

 following manner, the fact that normal parents may produce deaf 

 and dumb children. " During the period of gestation the mother 

 has a fall or receives a mechanical shock which seems unimpor- 

 tant. The shock is transmitted integrally b} 7 the intermediary of 

 the amniotic liquid to the entire surface of the brain of the fetus 

 which is not protected by an ossified cranium ; a cerebral agita- 

 tion is set up which is much feebler than that caused by a pro- 

 jectile, but which, acting upon a far more delicate nervous sys- 

 tem, produces analogous lesions and effects." That deaf-mute 

 parents may have normal offspring is consistent with this view 

 which does not involve the hypothesis of hereditary influence. — 

 Jour, de Phys., vol; vi, Jan.-Feb., 1916, p. 29. h. s. u. 



V. Concise Technical Physics ; by J. Lobing Aenold. . Pp. 

 viii, 275, with 294 figures. New York, 1916 (McGraw Hill Book 

 Co.). — This book is intended primarily for use in the first course 

 of theoretical physics in schools of engineering, and its differen- 

 tiating characteristic is extreme brevity. The author says: "This 

 book is intentionally laconic." "It contains nothing but what 

 can be required of every student." " It lays particular stress 

 upon fundamental conceptions, to the exclusion of too much 

 detail." "The book aims to give a thorough and comprehensive 

 basis on which to build further knowledge in each department of 

 the subject." 



The chief branches of physics are taken up in the following 

 order, which differs somewhat from the usual sequence: kine- 

 matics and mechanics of solids (67 pages), mechanics of fluids 

 (20), sound (23), heat (28), light (44), magnetism and static elec- 

 tricity (18), and current electricity (67). With few exceptions, 

 the text is as accurate as is consistent with its condensation, the 

 line diagrams are numerous and clear cut, and about eighty prob- 

 lems are suggested for solution. In the subject of light both the 

 ray and wave-front methods are used in the derivation of the 

 formulas. The only feature of the book which may be annoying 

 to a student who is acquainted with other texts on physics is 

 that the typographical errors are concentrated in the names of 



