A. M. Mayer—Acoustical Kaperiments. 267 
coronal light; but the rude apparatus did not work satisfacto- 
rily, and I confined myself to details of structure; indeed in 
my earnest gaze upon the novel phenomena I quite forgot the 
polarizing apparatus. 
Washington, D. C., Feb. 6th, 1872. 
Arr. XXXV.—Acoustical experiments, showing that the transla- 
tion of a vibrating body causes it to give a wave-length differing 
from that produced by the same vibrating body when stationary ; 
by AuFRED M. Mayer, Ph. D., Professor of Physics in the 
Stevens Institute of Technology, Hoboken, N. J 
THE APPARATUS. 
Four tuning-forks mounted on resonant cases and giving the 
note UT'*,=256 complete vibrations per second, were obtained. 
I will designate them as Nos. 1, 2, 8, 
os. 1 and 2 were brought into perfect unison by a process 
to be described. 
_ No. 1 was placed before a lantern, and just touching one of 
Its prongs was a small ball (5 or 6™™ diam.) of good cork, sus- 
on by a silk fiber. The images of the fork and of the cork- 
all were projected on a screen. 
_ No. 3 had one prong weighted with wax, so that it gave two 
beats a second with Fore 
No. 4 had the ends of its prongs filed off, until it also gave 
two beats per second with 1 or 2; thus No. 4 gave two 
vibrations a second more than No. 1, while fork No. 8 gave 
two vibrations a second less than No. 1. 
THE KXPERIMENTS. 
In the experiments, one to seven inclusive, fork No. 1 re- 
mains before the lantern, with the suspended cork-ball just 
touching one of its prongs. 
Exp. 1. Fork No. 2, screwed on its case. was held in the hand, 
at a distance of 30 to 60 feet from No. 1, and sounded ; the 
ll was projected from the prong of fork 1, which vibrated in 
unison with 2. 
Exp. 2. I stationed myself 30 feet distant from fork No. 1, and 
fork No. 2 was screwed off its case and vibrated in one hand, 
while the case was held in the other. I now walked rapidly 
toward fork 1, and after I was in regular motion, I placed the 
on its case, and just before I ceased walking I took it off; 
although, when I did so, I was only about a foot from fork 1, 
yet the cork-ball remained at rest against its prong. 
Exp, 3. Again I walked toward 1 as in Exp. 2, but I did not 
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