OBSERVATORIES AND THE DATA OBTAINED. 63 
The instrument used was a simple pendulum about a meter long, the bob weighing 
8.15 kg. A long pin passes freely thru a vertical hole in the middle of the bob and 
records on smoked glass below, with very little friction. V, 1.1 +. 
The reproduced seismogram represents the record as it was made by the pendulum. If 
the pendulum had remained stationary, the movements of the earth would have been 
just opposite to the recorded movements of the pendulum; but the record is complicated 
by the free swinging of the pendulum, which was subjected to little friction. The begin- 
ning of the movement can not be determined from theseismogram ; but from observation of 
a swinging electric light Mr. Clarke reports it as north to south. The seismogram shows 
a movement in the northwest-southeast quadrants with a fairly uniform amplitude of 
25mm. The direction of the pendulum’s swing changes, but shows little rotatory motion. 
Singularly, there is no large motion in the northeast-southwest quadrants, the motion in 
this direction being represented by an elliptic swing with its long axis directed to the north- 
east, but with only one-third the amplitude of the larger motion. The smallness of the 
friction, and the lack of exact information regarding the period of the waves, make it 
impossible to determine the true amount of the earth’s motion. 
Mr. Clarke gives the following account of the disturbance: 
“The first motion was a tremor that swiftly increased in intensity from north to south, 
and was quickly compounded into a twisting motion accompanied with severe upwari 
thrusts, a ‘churning motion.’ Then followed a jerky easterly and westerly motion, with- 
out the upward thrust, and again the twist; at the end the motion seemed to be south- 
easterly and northwesterly. Houses were jerked upward. Chimneys were thrown down 
at the latter part of the shock.” 
It is curious that the pendulum did not indicate more clearly the existence of rotatory 
motion; and it is still more curious that there was so little motion in a northeasterly 
direction, the direction of propagation of the disturbance. 
ALAMEDA, CALIFORNIA, 
Mills College Observatory. Prof. Josiah Keep, director. 
Lat. 37° 47’ N.; long. 122° 11’ W.; distance, 0.55° or 61 km.; direction, S. 61° E. 
Seismograms, sheet No. 3. 
The instrument used was a Ewing duplex pendulum; mechanical registration on smoked 
glass; V, 4. 
The seismogram shows a confused record with the beginning undetermined. The mark- 
ing point has jumped and must have been caught beyond the glass plate, as the record is 
evidently incomplete. The recorded amplitude corresponds to an earth-amplitude of 10 
mm., but it must have been much greater. 
SAN JOSE, CALIFORNIA. 
University of the Pacific. Prof. J. Culver Hartzell. 
Lat. 37° 20’ + N.; long. 121° 55’ + W.; altitude, 25 + meters; distance, 1.01° or 112 
km.; direction, 8. 45° E. 
Foundation, alluvium. 
Seismograms, sheet No. 3. 
The instrument used was a Ewing duplex pendulum, V, 4. 
The beginning of the movement is probably contained in the blur near ““W,” but it is 
impossible to determine in what direction the pointer moved from this spot; the pointer 
must have caught, for the seismogram evidently represents but a small part of the dis- 
turbance. The recorded amplitude corresponds to an earth-amplitude of 10 mm.; but 
it must have been much greater. 
