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ON THE EARTHQUAKE PHENOMENA OF JAPAN. 375 
not shown. aand dare needle points. The lower point d rests on a flat 
spring, 8, which can be raised or lowered by the screw T connected with 
a solid stand £. By raising b the point a is brought into contact with 
the end ofc. ff is a lead disc nearly sufficient to balance the portion of 
the pointer below b. 
The result of this arrangement is that if @ is moved relatively to }, 
this movement is magnified at the end of the pointer p. The sensitiveness 
of the instrument may be judged of from the fact that the pressure of my 
finger on the side of a stone column 2 feet square and 5 feet high is 
shown by a deflection of 4 or 5 millimetres at the end of the pointer. 
On the relief of pressure the pointer returns to its central position. To 
Fig. 2. 
Ww 
LLL LL LLL dl, 
obtain records, at intervals of every five minutes the current from an 
induction coil is sent down the pointer p, from which it passes as a 
spark through two strips of paper moving at right angles over the 
surface of a brass plate. One strip of paper moves north and south, and 
the other east and west. In this way a magnified representation of the 
position of the pendulum, drawn as a series of holes, is obtained. The 
magnification is about seventy times. Every hour a long contact makes a 
large hole. 
As a check to the observations two slightly different instruments are 
worked simultaneously by the same current, these instruments being on 
different columns in rooms about 60 or 80 feet apart. 
Thus far the results have not been analysed, but the following facts 
are clear :— 
1. Sometimes for days both instruments give a continuous series of 
holes in a straight line. 
2. Sometimes the holes are so multiplied by the trembling of the 
pointer that a broad line of holes is obtained. These tremors last from 
2 to 10 hours. 
3. Sometimes the pointer has slowly moved from side to side, giving 
a clearly defined set of holes marking two or three waves. The ampli- 
tudes of their waves, as shown on the diagram, are from 1 to 4 or 5 mm, 
