174 



SCIENCE. 



[N. S. Vol. III. NO. 57. 



stands before so humiliating an exhibition of 

 groundling bigotry as is presented by some of 

 the religious sects of the present day " (p. 472). 

 In striking contrast to this is the conclusion 

 reached by Mr. Phillips in his volume. In fact, 

 the whole of it seems to be written for the pur- 

 pose of proving the opposite opinion. He as- 

 serts that the farther back we go in the Vedic age, 

 the purer and higher do we find the conceptions 

 of divinity, man, duty, worship, a future state, 

 sacrifice, etc. Hence he avers : " The develop- 

 ment of religious thought in India has been uni- 

 formly downward — not upward — deterioration 

 and not evolution." He explains this by the 

 theory of a ' primitive divine revelation ' granted 

 to the Aryan forefathers, darkened and lost in 

 their descendants. He shows a good reading 

 knowledge of the Vedas in his discussions, but a 

 total ignorance of the methods which now obtain 

 among real scholars in treating the historical 

 growth of religious phenomena. The need of 

 such a work as that of Prof. Hopkins and of the 

 series which it commences, is amply indicated 

 by the appearance of such an essay as that of 

 Mr. Phillips. D. G. Beinton. 



SCIENTIFIC JOURNALS. 



THE AMERICAN JOUENAL OF SCIENCE. 



The February number of the American Jour- 

 nal of Science opens with an article by A. M. 

 Mayer, giving the results of an extended series 

 of experiments upon the modulus of elasticity 

 of bars of various metals and its variation with 

 change of temperature. This modulus was ob- 

 tained by transverse vibrations of bars of known 

 dimensions and density. Rods of steel, alumi- 

 num, brass, glass and American white pine were 

 employed. These were vibrated longitudinally, 

 held between the thumb and forefinger, and the 

 vibration-frequencies determined by the help 

 of the standard forks of Dr. Koenig's tonome- 

 ter in Paris. The application of Poisson's 

 formula (shown to hold closely true by special 

 experiments) gave the velocity of sound, and 

 the modulus of elasticity was then calculated 

 fi'om the usual mathematical relation connect- 

 ing these quantities. Special experiments were 

 employed to give the coefficients of expansion, 

 the densities, etc. The results are contained in 

 an extended table and further represented 



graphically in a series of plates. These show 

 that the decrease of the modulus of elasticity 

 of glass, aluminum and brass is proportional to 

 the increase of temperature ; straight lines re- 

 ferred to coordinates giving the results of ex- 

 periments on these substances. The five steels, 

 silver and zinc give curves, convex upwards, 

 showing that the modulus decreases more 

 rapidly than the increment of temperature; 

 while bell metal alone gives a curve which is 

 concave upwards ; its modulus decreasing less 

 than the increment of temperature. Bell 

 metal was found to be an alloy peculiarly well 

 suited for bells, as the intensity and duration 

 of its vibration were the same at 50° as at 

 0° ; all other substances showing a marked 

 diminution of intensity and duration of sound 

 at 60°. 



In a special discussion as to the acoustical 

 properties of aluminum, it is shown that this 

 metal is not peculiarly sonorous as ordinarily 

 believed. On the contrary, if a bar of aluminum 

 and a bar of brass having the same length and 

 breadth and giving the same note are struck 

 transversely so that the bars have the same 

 amplitude of vibration, the bars give equal 

 intensity of sounds ; but the bar of aluminum 

 from its low density and because of its in- 

 ternal friction will vibrate less than one-third 

 as long as the bar of brass. The peculiarity of 

 aluminum consists in this fact, that its un- 

 usually low density (2-7), combined with a mod- 

 ulus of elasticity of only 712 X 10", renders 

 this metal easy to set in vibration ; a transverse 

 blow given to a bar of this metal causes it to 

 vibrate with an amplitude of vibration greater 

 than that which the same energy of blow 

 would have given to a similar bar of steel or 

 of brass. 



It is true, however, that since aluminum 

 gives, from a comparatively slight blow, a great 

 initial vibration, and since its ■vibrations last 

 for a short time, this metal is peculiarly well 

 suited for the construction of those musical in- 

 struments formed of bars which are sounded by 

 percussion and the duration of whose sounds is 

 not desirable. 



On the other hand, there is one serious objec- 

 tion to the use of aluminum in the construction 

 of musical and acoustical instruments, and that 



