ISOSEISMALS: DISTRIBUTION OF APPARENT INTENSITY. 187 
more than half full, and fowls and other domestic animals were very much perturbed. 
There was a series of shocks, and reliable estimates of their duration vary from 20 seconds 
to 1 minute. The general direction seemed to be from southwest toward northeast, 
but others report a different direction. The Ukiah Valley is surrounded by mountains of 
considerable altitude, and it is probable that some of the shocks felt were reflected from the 
mountains. Hence it is that the earthquake is generally spoken of as a “twister.” 
The Observatory clock was not stopt, but it lost 6 seconds during the disturbance, which 
is equivalent to being stopt for that length of time and then set going again. The Observa- 
tory roof is built in two sections, which roll upon horizontal tracks, east and west, giving - 
an opening of about 1.3 meters for observation. When closed the two parts are fastened 
together by means of a hook and eye such as are used on screen doors. The hook rests 
in a horizontal position and the bend of the hook in a meridian plane. The effect of the 
earthquake was to unfasten this hook and open the roof to the width of about 20 centimeters, 
my recollection being that the eastern half was moved about twice as far as the western. 
The pier upon which the zenith telescope rests was apparently not damaged, but the tele- 
scope was thrown considerably out of adjustment. It was out about 15 seconds of are in 
azimuth and the vertical axis was out in both directions, but not much more than sometimes 
results from extreme changes in temperature. 
The first series of shocks was followed by three lighter shocks and the observed data for 
each are as follows: 

DURATION 






PaciFic STANDARD TIMR, Aout DIRECTION. INTENSITY. 
Apr. 184 5 13™ —£a.M. 408 SW. to NE. Severe 
Se tO 39. AL Me 10 SW. to NE. Medium 
ikon Tuk ste O A.M. 30 SW. to NE. Light 
20 12 30 53 a.m. — Very slight 


The times are correct within 2 or 3 seconds. 
I was in the observatory at the time of the second series of shocks, 10" 4", and perceived 
the effect of the movement in the striding level (east and west) of the zenith telescope. 
The bubble oscillated over about 2 divisions of the level. The value of one division is 
2.2’, and as the distance between the east and west leveling screws of the instrument is 
about 42 cm., the disturbance produced in the bubble was equivalent to the effect of raising 
and lowering one of the leveling screws by 0.0005 centimeter. This shock was felt very 
distinetly and it is probable that the north and south component of the motion was much 
greater than the east and west component. The fourth shock was not felt at all. It was 
detected during the progress of latitude observations, by a movement of the bubbles of the 
latitude levels. The oscillation (north and south) was about one-half of one division, and 
the value of one division is 1 inch. 
My estimate of the intensities for the four shocks given above would be, respectively, 
VII, IV, II, I. The Observatory is about a mile south of the city of Ukiah, and it seems 
certain that the earthquake was more severe in Ukiah than at the Observatory. The inten- 
sity of the first shock at Ukiah would certainly not be less than VIII, possibly LX. 
The direction of all shocks was southwest to northeast, according to bodily impression. 
Willets, Mendocino County (R. 8. Holway). — Brick chimneys were quite generally 
wrecked. The Buckner Hotel was completely demolished. One wall fell at the time of 
the shock, killing Mr. Taylor, the proprietor. The building finally fell at 10" 20 a. M. 
The structure was largely frame, with some brick veneer. The stores of the Irvine Muir 
Company were badly wrecked. Fire-walls fell; plaster, shelving, and goods were thrown 
to the floor. Brick walls fell in several other stores, and frame buildings were in some 
cases thrown from their foundations. Small cracks across some of the streets were re- 
ported, but they are not now visible. All brick buildings were damaged to some extent. 
A tank 2 or 3 miles to the east threw the water out on the northwest and southeast. 
Colonel La Motte, at the spawning station 5 miles north of Willets, stated that the water 
of a pool 8 to 12 feet in diameter and 2 feet deep splashed out on the south and south- 
east, wetting the pickets to a height of 18 inches. It did not splash out in any other 
