ON THE EARTHQUAKE AND VOLCANIC PHENOMKNA OF JArAN. 119 



that at A, and is similarly oiiented, stands beneath a wooden case on the 

 concrete floor of a cellar in the north-western corner of the Engineering 

 College at the Imperial University. It is without recording apparatus. 

 Its pointer floats over a scale, and its position is noted every day about 

 noon. When first set up on September 19, 1894, it had a period of 

 28 seconds. Its movements, which are indicated in millimetres, the sign 

 + meaning displacement towards the west and — towards the north and 

 east, have been gradual. They were as follows : — 



1894. During September — 1 or 2 



October 1-October 21 - 2 



October 21-October 31 +2 

 November 1-November 24—7 

 November 21- December 3+7 

 December 3-December 20—2 



Pendulum at M. — The object of this pendulum, which was installed 

 upon the same column as A, was somewhat different from that of the others 

 described in this series. It consisted of an aluminium boom loaded at its 

 outer end with a weight of about 300 grms. In addition to this it 

 carried a small vessel of ink from which a capillary tube projected, making 

 the total length of the boom about 4 feet 6 inches. This tube was 

 balanced, so that it barely touched the surface of a band of paper moving 

 at the rate of about 8 inches per hour. The force required to deflect the 

 boom one millimetre when applied at a distance of 4 feet fi'om the agate 

 pivot was approximately one milligramme. Before it was destroyed by fire 

 it recorded the occurrence of several local earthquakes, and, considering its 

 sensibility to tilting, it is probable that it would have recorded the gravi- 

 tational elastic waves of disturbances originating at great distances. A 

 necessary adjunct to such an apparatus in order to obtain an open diagram 

 is the addition of a quick speed feed for the paper, which must come into 

 action directly the pendulum commences to be deflected to the right and 

 left of its normal position. Such a device was designed for me by my 

 colleague, Mr. C. D. West, and it apparently works more satisfactorily 

 than the original form of this kind of apparatus which is found in the 

 Gray-Milne seismograph. 



Pendulum at N. — Sensibility, January 5, 1895, 1°=.3 mm. January 25, 

 1895, l°=2-5 mm., or 1 mm. = r'-03. The pendulum used at this 

 station was origiiaally at K. The hut was situated on the western side of 

 TJyeno Park, near to its southern extremity. It was sheltered by trees 

 on its eastern and southern sides. On its western side, where it was open, 

 there was a steep scarp leading down to the Shinobadzu Pond, which lies 

 in the bottom of a flat open valley. A, J, and K were on the plateau on 

 the opposite side of this valley, the heights of these stations being about 

 50 feet above the flat plain on which the greater portion of Tokio is 

 situated. The movements were usually small, seldom exceeding 7 mm. 



The westerly movement commenced from about 6 or 9 p.m., and con- 

 tinued until about noon next day ; that is to say, that about the time ivhen 

 the instruments u2)on the opposite hill or 2)lateau were goi^ig eastwards, the 

 instrument at Uyeno went towards the ivest, and vice versa (fig. 10, p. 136). 



Pendulum at 0.— Sensibility, January 12, 1895, l°=l-5 mm. 

 January 22, 1805, l°=:l-5 mm. Station O was situated at a place about 

 20 yards to the south of J. It only differed from the instrument at this 

 latter station in the fact that the boom of the pendulum pointed from 

 west towards the east, and it therefore recorded north and south motion. 



