the circumference were 165 m bn: fo rther apart than when the 
Chemistry and Physics: : 417 
SCIENTIFIC INTELLIGENCE. 
I. CHEMISTRY AND PHYSICS, 
1, Apparatus for the direct determination of the velocity of sound in 
atmospheric air ; by Dr. E. C. O. Neumann.—This ingenious little appa- 
ratus consists of a box of wood (82 cm. hie 66 cm em. hig 
divided by vertical partitions in suc nner as ae orm two canals, 
running from one corner, F, of the box, ee “first only to the middle, the 
other by a winding course to near the same point so as to be about six 
meters longer. A “little gun is placed on top of the box; when fired the 
sound is Rab be through a square tube to the corner F, where it di- 
vides; one part goes directly to the middle, A, of the front side ‘of the 
box, and ely a short wire, f, fastened upon a thin caoutchouc mem- 
brane by means of a small piece of wood; the other part of the sound 
traverses the six meters of winding tube, atid at strikes the membrane, 
closing’ an peas B (near the latter 
rovided wit lackened wire, g (1 mm. diam.), In front of these 
wires a disk, Soviet with white paper, can be made to rotate around a 
horizontal axis. 
When this disk is at rest the report passing in at F will soon push the 
wire f against the paper, leaving a black spot—and when the six meters 
have been traversed, the other vart of the sound wave will push the wire 
tion. But when the disk made one turn per second, these two marks on 
was 
at rest. Then we evidently save the velocity, v, of sound by the propor- 
on 
v : 2a15c.m.:: 6m. ; 164mm., 
or v==346™-2. The neces was 22° C.; a good approximation for 
a first trial—Pogg. Ann., 1866, exxiii, 307-311 2. 
2. Interference apparatus for sound-waves ; @. QuixcK cxe.—This ap- 
aratus is based upon Herschel’s idea of applying branching tubes, and 
admits of subjective and objective experimentation ; it also may be ap- 
plied to the study of secondary tones nigel a etc., like Helmholtz’s 
resonators. The simplest kind consists of tw 
bent glass tubes DCBEF and GHILM provided a Des 
i A B Ie 
3 
ec 
or 
w 
o 
= 
> 
3 
oO 
= 
ies) 
- 
es 
o 
a 
Pe cs 
A 
b> 
a 
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rubber tube, which is put into one ear aap se ty oe 
other is well closed; at K is another rub 
leading to a source of sound, viz., the vibeating branch of a tuning ge : 
G a 
or its middle rod, or into the box of a monocho 
a sho 
e ILEB engths — 
— thas IHCB. If a tuning fork is used, and the length of MF 
properly adjusted (the interference-tube tuned), then only the octave is 
ear. an 
the prime being destroyed by interference. If 
FM or DG is closed by pressure Y with the finger, the fundamental tone 
the tuning fork is heard again. 
