A. M. Mayer on the Experimental Determination, etc. 128 
Art. XVI.—On the Experimental Determination of the relative 
Intensities of Sounds ; and on the measurement of the powers o 
various substances to Reflect and to Transmit Sonorous Vibra- 
tions; by ALF . Mayer, Ph.D., Professor of Physics 
in the Stevens Institute of Technology. 
(Read before the National Academy of Sciences, in Cambridge, Nov., 1872.) 
(Concluded from page 46.) 
WHEN the resonators have such distances from their corres- 
ponding sounding bodies that the phases of the impulses on 
the membrane are opposed while their intensities are different, 
a residual action is given, and the intensity of this action on the 
membrane will depend on the relative intensities of the sources 
of sound and the relative distances at which the resonators 
are placed. It may here be interesting to consider the simplest 
case, that is, when the intensities of vibration at the two sources 
of origin of the sounds are the same, and the two resonators are 
placed at various distances from these points of origin, but 
always differ in their distances. by one half wave-length. Let 
us call A one of the resonators, B the other. Let A be succes- 
sively placed at distances from its sounding body equal to 1, 2, 
3, &c., wave-lengths, and B successively at distances equal to 14, 
24, 31, &c., wave-lengths) When the resonators are in the 
above positions we will suppose that the phases of vibration 
reaching the membrane are opposed. The following table gives 
the calculations made on the assumption that the intensities 
of the vibrations diminish as the reciprocals of the squares of 
their distances from the sounding bodies: 
A’s dist. in A. B’s dist. in A. Ratios of Intensities. i Effects. 
1 1°5 444 556 
2 2-5 640 360 
3 3°5 734 266 
4 4°5 “7-0 210 
5 5° 826 : 174 
6 65 B54 146 
7 75 “S71 129 
8 8°5 885 115 
9 9°5 ‘897 103 
10 10°5 907 093 
11 11°5 914 086 
12 12°5 921 079 
13 13°5 927 073 
24 24°5 "959 041 
25 25°5 961 039 
We have projected these related numbers in the accompany- 
ing curve, whose abscissas represent the distances of A from 
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