ATMOSPHERE AND THE ACOUSTIC EFFICIENCY OF FOG-SIGNAL MACHINERY. 291 
Test No. 2 (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 
differences, 
sounding and 
silent. 
(se—se 1 ). 
Power emitted 
as sound and 
consumed in 
driving piston 
in H P. 
(«0- 
Acoustic 
efficiency. 
(t=»/W). 
0 c. 
1 
10 -o 
3 
•7 
5 1 
0 -98 
0 13 
0 026 
2 
11 -9 
5 
•1 
8 -0 
1 '55 
0 '28 
0 035 
3 
13 -8 
5 
•5 
9 5 
1 '72 
0 '33 
0 035 
4 
15 -7 
6 
•4 
12 2 
2 '53 
0'57 
0'047 
5 
17 6 
6 
•4 
12'9 
2 '36 
0 '53 
0 041 
6 
19 '4 
7 
•o 
15 3 
2 '56 
0 '63 
0 041 
7 
21 4 
8 
T 
18 7 
2 '46 
0'71 
0 '038 
8 
23 2 
8 
■3 
19 9 
1 '65 
0 '48 
0 '024 
9 
25 "1 
9 
•o 
22 4 
1 '75 
0 '55 
0 '025 
10 
27 -0 
10 
•o 
26 -4 
1 '77 
0 '62 
0 024 
Test No. 3. September 16, 1913. 
No. of 
observations. 
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 
38 -5 
3'7 
3 '7 
1 T 
4'9 
0 '58 
2 
50 '5 
4-0 
4 '0 
1 0 
o ‘1 
1 16 
3 
60'3 
4'4 
4 '2 
0 '9 
5 '3 
1 '31 
4 
70 '0 
5 '0 
4'9 
0'9 
5 '85 
1 '46 
5 
79 -8 
5-6 
5 '6 
0 '8 
6 '5 
1 '59 
6 
89 '6 
6 '0 
6 '0 
0 '8 
6 '8 
1 '83 
7‘ 
99'3 
6 *7 
6 '8 
0 '8 
7 55 
2 '05 
8 
109 -0 
7 T 
6 '9 
0 '8 
7 '8 
1 '90 
9 
118-8 
7 "7 
7 '5 
0 '8 
8 '4 
1 '66 
10 
128 '6 
8 '0 
8 '2 
0 '7 
8 '9 
1 '25 
11 
138 -2 
8 '8 
9'0 
0 '7 
9'7 
0 '82 
12 
148 '0 
9'3 
10 '3 
0'7 
10 5 
0 '64 
Results of Test 3, September 16, 1913. Yalves admitting sounding and driving air re-adjusted. 
2 Q 
VOL. CCXVIII.-A. 
