ox THE IvAKTIIQr.VKE I'lIKNOMEXA <)1' JAPAN'. 



249 



ai'e yet required to destroy flic vertical motion of earthquakes, noraetbing 

 of practical value will have been done to mitig;»te the serious results which 

 accompany destructive earthquakes by the elimination of their horizontal 

 nuivements. 



,\ras was 



0)1 the Edahlishmciit of an UnJen/rdUiid Olisireatory, 



la December last year I visited the Takashima Colliery, near Nagasaki, 

 with the object of making investigations preparatory to the establishment 

 of an underground observatory. The phenomena which I had the inten- 

 tion of observing were : — 



1. Earth-tremors. — It has been observed thai these microscopic raove- 

 ineuts of the soil accompany baiotnetric falls, and it is therefore probable 

 that they may hold some relationship to the escape ot gas which in 

 certain parts of the Takashima mine is a source of considerable danger. 

 At tliis mine the gas escapes several hours before any marked changes 

 take place in the baronietrictil column. Should it be found that the 

 occurrence of tremors precedes barometric fluctuations the utility of the 

 observations is obvious. 



The instruments to be used for observation ai-c tromometers, like those 

 employed by Bertelli and Rossi in Italy, and microphones in a telephonic 

 circuit. During my short stay at the mine, I found that a microphone 

 placed in an unworked part of the mine was at times very .active. 



2. The observation of delicate levels for the purpose of recording any 

 variations which may take place in the inclination (f the ground. Since 

 [ left the mine, Mr. John Stcddart, the chief engineer, who has under- 

 taken these various investigations, writes me that he commenced 

 observations with the levels on the surface of tlie ground. Owing to a 

 gradual subsidence, due to the underground excavations, Avhich is 

 evidenced by nunierons cracks on the surface, the changes in the levels 

 are so great that it will be necessary to establish them unelerground. 



3. The measurement of the sinking of the underground excavations. 

 As the mine, which is very large, extends a long di.stance beneath the 

 ocean, it is not unlikely that some connection may be found between the 

 raovemcnt of the roof and the tides. ^Er. Stoddart tells me that the 

 contrivance for indicating these effects yields such marked results that a 

 number of similar apparatus are being made for distribution in ditlerent 

 parts of the workings. 



4. The observation of earth-currents. Whilst I was at the mine, 

 feeble currents were visible on a line only sixty yards in length. 



In consequence of a fire which broke out in the mine sliortly after T 

 left, it, is o)dy quite recently that Mr. Stoddart has had opportunity to 

 turn his attention to these investigations. At a future period I trust 

 that I may be able to report upon them. For facilities enabling these 

 observations to be made, my thanks are due to the ]\ritsu Bishi Company, 

 who are the owners of tlie mine. 



TJ art I, -tremors and Eartli-jnil'iations. 



For the present, the observations on earth-tremora in Tokio have 

 heen discontinued. The observations on changes in inclination of the 

 ground, as shown by the movements in the bubbles of levels and in the 

 position of the stile of a penduluu'. relatively to a point beneath it, are 



