290 DR. LOUIS VESSOT KING ON THE PROPAGATION OF SOUND IN THE FREE 
Test No. 1 (continued). 
No. of 
observation. 
Mean pressure 
above 
atmosphere, 
lbs./sq. in. 
Air consumption 
in cubic feet 
per second. 
Maximum power 
possible iu H.P. 
(W). 
Temperature 
differences, 
sounding and 
silent 
(50-50')- 
Power emitted 
as sound and 
consumed in 
driving piston 
in H.P. 
(»)• 
- 
Acoustic 
efficiency 
(v = tcfW). 
1 
9 '8 
7 ’9 
10 -9 
°C. 
1 -40 
0-39 
0-036 
2 
11 -7 
9-0 
13-9 
1 -97 
0-62 
0-044 
3 
13-6 
9 9 
16-9 
2-34 
0-81 
0-048 
4 
15 4 
10-9 
20-5 
2-58 
0-99 
0-049 
5 
17 -3 
11 -4 
23 1 
2-95 
1 -19 
0-051 
6 
19 -1 
13 -0 
27 -9 
3 -44 
1-57 
0-057 
7 
19 '9 
13 3 
29 2 
3 -44 
1 -GO 
0-056 
8 
21 -0 
14 1 
31 -9 
3-22 
1 -60 
0-050 
9 
22-9 
15 -0 
35 -8 
3-15 
1 ‘66 
0-046 
10 
24-7 
16 1 
40 0 
3 -03 
1 -70 
0-042 
11 
26-5 
18 -3 
47 ‘3 
2-80 
1 -80 
0 -038 
Test No. 2. September 15, 1913. 
No. of 
observations. 
Mean pressure 
above 
atmosphere, 
cm. mercury. 
Pressure dro] 
cm. mercury. 
iu 6 seconds. 
Silent. 
cm. mercury. 
Pressure increase 
in 6 seconds due 
to compressors, 
cm. mercury. 
Mean pressure 
drop in 6 seconds, 
cm. mercury. 
Resistance 
change 
of differential 
thermometers, 
sounding and 
silent. 
0 - *')• 
ohms. 
1 
51 -6 
1 -75 
1 -45 
1 -05 
2 1 
0 -40 
2 
61 5 
2 0 
1 -8 
1 -o 
2 9 
0 -63 
3 
. 71 5 
2 -2 
2 -25 
0 -9 
3 T 
0 -70 
4 
81 -2 
2 -8 
2 -7 
0 -9 
3 -6 
1 -03 
5 
91 -1 
2 65 
2 95 
0-9 
3 -6 
0 -96 
6 
100 -8 
3 -1 
3 -25 
0 -85 
4-0 
1 -04 
7 
110 -7 
3 8 
3-7 
0-8 
4 6 
1 00 
8 
120 5 
4-2 
3 8 
0 7 
4-7 
0 -67 
9 
130-4 
4-5 
4 "26 
0-7 
5 1 
0 -71 
10 
140 T 
5 -1 
4 -8 
0 -7 
5 -7 
0 -72 
Fig. (ii.). Characteristics of the diaphone. 
Results of Test 2, September 15, 1913. Air consumption halved by throttling. 
