292 DR. LOUIS YESSOT KING- ON THE PROPAGATION OF SOUND IN THE FREE 
Test No. 3 (continued). 
No. of 
observations. 
Mean pressure 
above 
atmosphere, 
lbs./sq. in. 
Air consumption 
in cubic feet 
per second. 
Maximum power 
possible in H.P. 
(W). 
Temperature 
difference, 
sounding and 
silent. 
(86-86'). 
Power emitted 
as sound and 
consumed in 
driving piston 
in H.P. 
(«>). 
j 
Acoustic 
efficiency. 
(? = w/W). 
1 
7 '4 
8 6 
9 -7 
° C. 
1 43 
0 -43 
1 
0 044 
2 
9 7 
9 0 
12 3 
2 85 
0 -90 
0 073 
3 
11 -6 
9 3 
14 o 
3 -22 
1 06 
0 073 
4 
13 5 
10 3 
17 -7 
3 59 
1 30 
0 074 
5 
15 '4 
11 4 
21 -4 
3 -91 
1 57 
0 074 
6 
17 2 
12 0 
24 2 
4 -50 
1 -88 
0-078 
7 
19 1 
13 3 
28 o 
5 04 
"2 36 
0-083 
8 
21 0 
13 -7 
31 1 
4-67 
2 25 
0 072 
9 
23 0 
14 8 
35 2 
4'08 
2 11 
0 -061 
10 
24 -8 
15 7 
39 -0 
3 -08 
1 -69 
0 043 
11 
26 6 
17 1 
44 3 
2 02 
1 -21 
0-027 
12 
28-6 
18 -5 
49 5 
1 -57 
1 01 
0 -020 
Test No. 4. September 16, 1918. 
No. of 
observation. 
Mean pressure 
above 
atmosphere, 
cm. mercury. 
Pressure drop 
Sounding, 
cm. mercury. 
in 6 seconds. 
Silent. 
cm. mercury. 
Pressure increase 
in 6 seconds due 
to compressors, 
cm. mercury. 
Mean pressure 
drop in 6 seconds 
cm. mercury. 
(Pi-P'i)- 
Resistance 
change of 
differential 
thermometers, 
sounding and 
silent. 
(*-*') 
ohms. 
1 
40 0 
0 -85 
0 -65 
1 05 
1 -8 
0 22 
2 
51 -7 
1 6 
1 6 
1 0 
2 6 
0 -62 
3 
61 6 
1 85 
1 95 
0 9 
2 -8 
0 94 
4 
71 4 
2 3 
2 25 
0 -9 
3 2 
1 08 
5 
81 -3 
2-55 
2 -55 
0-8 
3 35 
1 25 
6 
91 1 
2 9 
3 0 
0 -8 
3 75 
1 -35 
7 
100 8 
3-6 
3 55 
0 -8 
4-40 
1 44 
8 
110-7 
3 -8 
3 -7 
0 -8 
4 55 
1 49 
9 
120 -5 
4 25 
4 0 
0 75 
4 85 
1 08 
10 
130 4 
4 6 
4 3 
0 -7 
5 15 
0 -89 
11 
140 1 
5 05 
5 0 
0 -7 
5 -75 
0 -87 
12 
149 6 
(6-1) 
5 -9 
0-7 
6 -7 
0 -84 
13 
159 1 
7 1 
6 8 
0 -7 
7 65 
0 99 
Cu.ft l 
sec. 
TO 
8 
6 
4 
2 
O 
El. 
30 
-20 
-IO 
oA sA> 
Acou 
stic 
iffic: 
, ~ 
Art 
---"J 
Acoustic, out] 
^-*L 
ut i] 
t H.P 
f= 
<3 
o 
Jj 
Ps 
6 
4 
2 
4 
6 8 IO 12 14 16 18 20 22 
Pressiixe-LLs. per sg-in. 
Fig. (iv.). Characteristics of the diaphone. 
Results of Test 4, September 16, 1913. Conditions as in Test 3, with air consumption halved by 
throttling. 
