OBSERVATORIES AND THE DATA OBTAINED. 75 
At 15® 31™, (f), vibrations propagated along major arc, according to Professor Omori. 
The large amplitudes shown, both at the beginning of the second preliminary tremors 
and in the long waves are due to approximate synchronism of periods of the waves and 
the pendulum. 
BIDSTON, ENGLAND. 
Liverpool Observatory. W. E. Plummer, director. 
Lat. 53° 24’ N.; long. 3° 04’ W.; altitude, 54 meters; distance, 74.81° or 8,317 km.; 
chord, 7,739 km.; direction, N. 33° E. 
Foundation, sandstone. 
Seismograms, sheet No. 1. 
The instrument used was a Milne horizontal pendulum, east component; photographic 
registration. T,, 18.7 seconds; V,6.1; J, 530 meters; ¢€, 1.057; M, 255 gm.; L, 15.6 em. 



First SECOND 
R P 
Se Tene etl isl table ate ues hes a 
min. min, min. min, min. mm. 
East component Dae 34.0 48.2 51.6 54.3, 56.3 to 58.2 17 + 
Interval . 11.8 Zieo BOT 39.1 



Duration, 4.1 hours. The regular waves can be recognized by their greater period, 
which amounts to 24 seconds against 19 seconds during the principal part; this becomes 
still shorter during the strongest part of the disturbance. A comparison with the seis- 
mograms of Edinburgh, Paisley, and Kew also help to identify this phase, tho there is 
not so marked a change in amplitude at its beginning as in the other seismograms men- 
tioned. 
UPSALA, SWEDEN. 
Meteorological Observatory of the University. Prof. Dr. H. H. Hildebrandsson, 
director. 
Lat. 59° 51.5’ N.; long. 17° 37.5’ E.; altitude, 16 meters; distance, 76.80° or 8,538 
km.; chord, 7,914 km.; direction, N. 19° E. 
Seismograms, sheet No. 9. 
The instrument used was a Wiechert inverted pendulum, two horizontal components ; 
mechanical registration on smoked paper. 
(1) North component: 75, 6.8 seconds; V, 230; J, 2,650 meters; ¢, 3; M, 1,000 kg.; 
L’, 11.5 meters; L, 1 meter. 
(2) East component: 7, 5.3 seconds; V, 270; J, 1,900 meters: ¢, 3; M, 1,000 kg.; 
L’, 11.5 meters; L, 1 meter. 


| 
First SECOND 






R PE P 
PRELIMINARY Acerbis ceca we Max Ampuiirupe, | Perriop. 
m,. 8. m,. 8. m, 8. ™m, 8. m,. 8. mm, 8ec. 
55 00 46 
(1) North component} 24 51 34 43 50 20 |54 05 59 15 50 
02 45 57 15 
(2) East component 24 51 34 45 eee 0200060155) 54 00 15 
Average .. .| 24 51 34 44 50 20/538 02? 
intervals 2-7) te 23 22-16 37° 52 |40 34? 

Duration, 3 hours. The first and second preliminary tremors are especially well de- 
fined. The amplitudes of the long waves are about equal on the north and on the east 
components; what appears to be the principal part on the east corresponds to dying down 
of regular waves on north. It is curious that the strongest motion of east occurs when 
