170 Dr. A. M. Mayer's Researches in Acoustics. 



permit of any general deductions, it appears that the presence 

 of nickel in a low carbon steel lowers its modulus of elasticity. 

 Thus, steels No. 3 and 4, having respectively *47 and "51 per 

 cent, of carbon, have a modulus of 2130 xlO 6 ; while steel 

 No. 5, containing "27 per cent, of carbon and 3 per cent, of 

 nickel, has a modulus of 2080 x 10 6 , which is 2*35 per cent, 

 lower than that of steels Nos. 3 and 4. 



The presence of nickel in a steel may, in a diminished 

 degree, have the effect of carbon in lessening the lowering of 

 the modulus when the temperature of the steel is increased. 

 Thus the percentage of the lowering of the modulus, by 

 heating from 0° to 100°, of steel [No. 5 containing 0'27 of 

 carbon and 3 per cent, of nickel, is the same as that of steel 

 No. 3 with 0*47 per cent, of carbon. 



If a bar of any one of the substances experimented on is 

 struck with the same energy of blow, by letting fall on the 

 centre of the bar a rather hard rubber-ball from a fixed height, 

 the sound emitted by the bar diminishes in intensity and in 

 duration as the temperature of the bar is raised. Thus : 



Brass at 0° vibrates during 75 sees. ; at 100° it vibrates during 45 sees 



Bell-metal ,, „ 55 „ „ „ 15 



Aluminium „ ,, 40 „ „ „ 12 



J. & C. Cast Steel „ „ 80 „ „ „ 5 



Bessemer Steel „ „ 45 ,, „ „ 1*5 



St. G-obain Glass „ „ 6 „ ., „ 3'5 



Zinc at 0° vibrated during 5 sees. ; at 20° only during 

 1*5 sec. At 62° it vibrated for so short a time that it only 

 gave three beats with forks of 1090 and 1082 v. s. At 80° it 

 was not possible to determine the pitch of the bar, and at 100° 

 the bar when struck gave the sound of a thud. The bar of 

 silver acted in a similar manner to the bar of zinc — it was 

 even less sonorous than zinc, — thus flatly denying the " silvery 

 tones " attributed to it. 



These phenomena do not depend on the fall of modulus, but 

 on changes in the structure of the metal on heating it, which 

 cause the blow to heat the bar and not to vibrate it. 



Bell-metal was found to be an alloy peculiarly well suited 

 for bells, as the intensity and duration of its vibrations were 

 the same at 50° as at 0°, all other substances showing a 

 marked diminution of intensity and duration of sound at 50°. 



A bar of unannealed drawn brass, after it has been heated 

 to 100°, has its modulus at 20° increased -j^ per cent. 

 (See Table III. and fig. 11, p. 188.) 



In this research I had the good fortune to have the 

 assistance of Dr. Eudolph Koenig, of Paris. He not only 

 placed at my service the resources of his laboratory and 



