OBSERVATORIES AND THE DATA OBTAINED. 105 
CALCUTTA, INDIA. 
Alipore Meteorological Observatory. G. W. Kiichler, assistant meteorological reporter. 
Lat. 22° 32’ N.; long. 88° 20’ E.; altitude, 6.5 meters; distance, 112.72° or 12,531 
km.; chord, 10,607 km.; direction, N. 31° W. — 
Foundation, marshy alluvium; 100 km. from the sea, and far from mountains. 
Seismograms, sheet No. 1. 
The instrument used was a Milne horizontal pendulum, east component; photographic 
registration. T,, 18 seconds; V, 6.1; J, 490 meters; e¢, 1.10; angular displacement, 
1 mm. = 0.38’; M, 255 gm.; ZL, 15.6 cm. 


mea | 
First Pre-|SEconD PrE-| REGu- A: 
LIMINARY | LIMINARY LAR Max Lage 
Tremors. | TrEmMoRS. | WAVES. ee 
min. min. min. min. mm. 
East component . .| 29.2? 39.4 05.6? 17.3 Li 
Intervalwe el) 16507 26.9 Hosier 





Duration, 4.1 hours. It is difficult to determine the exact time of beginning, as there 
was a slight disturbance of the beam. The time of the second preliminary tremors is less 
doubtful. 
BOMBAY, INDIA. 
Government Observatory. N. A. F. Moos, director. 
Lat. 18° 54’ N.; long. 72° 49’ E.; altitude, 11 meters; distance, 121.19° or 13,472 
km.; chord, 11,099 km.; direction, N. 17° W. 
Foundation, basaltic trap. 
The instruments used were: 
(1) Milne horizontal pendulum, east component; photographic registration. Seis- 
mograms, sheet No. 2. 7’, 18 seconds; V, 6.1; J, 490 meters; angular displacement, 
Imm. = 047"; M, 255 gm.; DL, 15.6 cm. 
Colaba horizontal pendulums, two components; mechanical registration with ink on 
paper. Seismograms, sheet No. 15. 
(2) North component: 7,, 24 seconds; V, 3; J, 430 meters; angular displacement, 
1imm. = 0.27"; M, 25 kg.; L, 92+ cm. 
(3) East component: 7, 37 seconds; V, 5; J, 1,700 meters; angular displacement, 
Imm. = 0.14"; M,25kg.: L, 92+ em. 
Each one of the Colaba pendulums consists of a mass of about 25 kg., supported on a 
horizontal beam about 90 cm. long. The solid friction is large, sufficient to stop the 
vibration of the pendulum in a single vibration if its amplitude is not more than a few 
millimeters. 








SEcOND PRE- 
LIMINARY 
TREMORS. 
REGULAR 
AVES. 

min. min. 











(1) East component . 40.8 11.8 
(2) North component 42.5? us 
(3) East component . 42.57 aS 
Average. . 40.8 11.8 
Interval . 28.3 59.3 




Duration, 3.4 hours. (1) gives a better value of the time of arrival of the second 
preliminary tremors than the average on account of the strong friction of (2) and (3); 
and therefore its value is used in preference to the average of the three instruments. The 
