ATMOSPHERE AND THE ACOUSTIC EFFICIENCY OF FOG-SIGNAL MACHINERY. 275 
Table 4.—Long Range Acoustic Survey, August 30, 1913. 
Father Point Meteorological Observations. 
Barometer, 29 '65. Air temperature : dry bulb, 48° F.; wet bulb, 47° F. 
Wind: very light; velocity: 9-10 a.m., 3 miles per hour; 10-11 a.m., calm. Direction from W. Weather hazy. 
Clouds moving very slowly from W. Sky completely clouded over. 
Phonometer Readings. 
Position 
No. 
Phono¬ 
meter. 
Position 
No. 
Phono¬ 
meter. 
Position 
No. 
Phono¬ 
meter. 
Position 
No. 
Phono¬ 
meter. 
Position 
No. 
Phono¬ 
meter. 
0 
2-5 
30 
0'4 
60 
0'2 
90 
120 
0-4 
1 
1 '4 
31 
0 '4 
61 
0'2 
91 
0 T 
121 
— 
2 
1 3 
32 
0 '3 
62 
0'2 
92 
0 '2 
122 
0'2 
3 
2-3 
33 
0'4 
63 
0'3 
93 
O'l 
123 
0'3 
4 
0'5 
34 
0'2 
64 
O'O 
94 
0'2 
124 
0 '3 
5 
0'4 
35 
0 '4 
65 
0 '3 
95 
0'3 
125 
0'3 
6 
0'8 
36 
0'3 
66 
0'3 
96 
0 T 
126 
0'35 
7 
1 '0 
37 
0 '2 
67 
0 '0 
97 
0 '2 
127 
0'4 
8 
0 ■5 
38 
0'3 
68 
0 T 
98 
O'l 
128 
0'6 
9 
1 '0 
39 
0 '2 
69 
0'1 
99 
— 
129 
0'5 
10 
l'l 
40 
— 
70 
0 T5 
100 
0 T 
130 
0'6 
11 
0-7 
41 
0 '3 
71 
0'2 
101 
O'l 
131 
0'6 
12 
0 '4 
42 
0 '3 
72 
0-2 
102 
0 '2 
132 
0'7 
13 
0'3 
43 
0'2 
73 
0 '2 
103 
O'l 
133 
O '7 
14 
0 6 
44 
0 3 
74 
01 
104 
O'l 
134 
0'8 
15 
0'6 
45 
0'3 
75 
0-0 
105 
0'3 
135 
0'7 
16 
0'5 
46 
0'1 
76 
0 -0 
106 
0'35 
136 
0'8 
17 
0-4 
47 
0'3 
77 
0 T 
107 
0'3 
137 
0'7 
18 
0 3 
48 
0-1 
78 
O'O 
108 
O'l 
138 
0'6 
19 
0'3 
49 
01 
79 
01 
109 
O'l 
139 
0 '8 
20 
0'3 
50 
0'2 
80 
O'O 
110 
0'3 
140 
1 '4 
21 
0 '4 
51 
0'2 
81 ■ 
O'l 
111 
0 '2 
141 
2'0 
22 
0 '4 
52 
0'2 
82 
0'2 
112 
0 '2 
142 
1 '6 
23 
0'5 
53 
0-2 
83 
0'05 
113 
0'3 
143 
2 '8 
24 
0'6 
54 
01 
84 
0 T 
114 
0'2 
144 
3'0 
25 
0'3 
55 
0'3 
85 
O'l 
115 
0'3 
145 
4 ’5 
26 . 
0'4 
56 
01 
86 
0 '05 
116 
0'2 
27 
0'2 
57 
0 '2 
87 
O'l 
117 
0'3 
28 
0'3 
£8 
0'3 
88 
0 T 
118 
0'3 
29 
0 '4 
59 
0-3 
89 
0'2 
119 
0 '3 
Remarks. 
8.28 a.m. Left Rimouski wharf. Light fog over sea. Sea unrul&ed. Signal just audible. 8.29-8.59 a.m. Course to 
Father Point wharf. Signal heard over entire course. 8.56 a.m. Ship abeam Father Point wharf. Phonometer reading, 
0 '9. Echo audible 20 seconds. 
0. Time, 9.01 a.m. Started course from fog-signal. 8. Air temperature, 50° F. Echo audible 10 seconds. 9. Sky heavily 
overcast; light rain. 22. Rain stops. 33. Sky overhead clears, and sun commences to shine. 37. Sun shining brightly; 
smoke from ship hangs low. 40. Signal not heard. 55. Breeze freshening. 64. Signal barely audible. 67-69. Signals 
just audible. 71-73. Time, 10.20 a.m. Ship turns at end of course. Distance from fog-signal, 8'64 nautical miles. 
75-76. Signals barely audible. Air temperature, 52° F. 77. Signal just audible, but distinct. 80-81. Signal barely audible. 
Termination of signal distinct. 99. Signal not heard. 102. Noticeable increase in audibility. Air temperature, 50° F. 
105-107. Marked increase in audibility. Sky overcast. 133. Echo of signal marked. 144. Echo audible 15 seconds. 
Control Observations. 
End of Father Point wharf. —Mean of four phonometer readings, 4 '5. Echoes heard for 23, 19, and 21 seconds. 
Maximum of echo (5 to 6 seconds after termination of second blast) gave phonometer reading about 0 '2. Interval between 
3-second blasts not detectable in echo. 
Control station. —Mean of nine phonometer readings, 7 '0. 
Mean air pressure operating diaphone, 19 '9 lbs./sq. in. above atmospheric. 
2 o 
VOL. CCXVIII.-A. 
