ON THT K.VIITIIQUAKI' rilENOMK.NA OF JAPAN. 



251 



iis been 

 )rds are 

 1 efirth- 

 and I 

 lem. 



•o'tncZ 



mixA, but 

 10 move- 

 tiate any 



ui of tlie 

 isly tbreo 

 he lowest 

 Id founda- 

 eat deptli, 

 niT a eon- 

 to obtain 



phone and 



imonting— 

 > of sounds 

 and the 



t docs not 



continues 



d to tliose 



md. 



on, accom- 

 /iodicity or 



tlic under- 

 mainland 

 ^- convinced 



onsidcrablc 

 carburetted 

 oter nndcr 



Ice from tlu' 

 the undev- 



i-o its being 

 toal strata. 

 Ill the brief 



increase in 

 las a rule to 



also seems 



liighly probable that au increase of vibratory motion in tlio coal strata 

 wonld tend to faciJitate the outflow of gases contained therein in even a 

 greater ratio than v,onld the diminution of atmospheric pressnre. My 

 personal experience in mining tends entirely to snpport this deduction, 

 as I have invariably found that in places where the outflow of gas was 

 fairly constant as a general rule, it always increased to a greater or less 

 extent when what is technically called any ' working ' of tlie strata took 

 place. 



For the purpose of obtaining more reliable statistics on this head, I 

 have arranged with Mr. F. liinger of Nagasaki to erect the microseis- 

 monicter at his observatory on the mainland, eight miles from this island, 

 and Ave shall be able, by making simultaneous observations, to connect liis 

 notes with those made at the observatory at the mine. Of course it 

 would be preferable to have the maiTiland observatory situated at a point 

 much closer to the mines than this one is, but there! is no place nearer 

 where we can be sure of having a reliable observer. 



(Hiservallois un J'Jur/Ji-rurn'iLts, (]'■'•. 



Owing to my inexperience in magnetic observation and the difhcnlty 

 in getting suitable apparatus consti-uctcd or erected down here, I havo 

 only begun to make regular observations durintr the current month. 

 Previous to this, however, 1 have been making isolated experiments with 

 such rough-and-ready apparatus as could be constructed on the spot. 



Tiie results are brieliy as follows: — 



With one wire connected with an iron bar fixed in the line of a 

 fault below-ground, and the other end fixed to a similar bar inserted in the 

 strata at a distance of about 100 yards, there vvas a considerable deflection 

 in a home-made <r dvanometer. 



With both ends connected with the coal strata below ground, but 

 away from the vicinity of any fault, the deflection was hardly perceptible. 



With one end flxed to the rod inserted in the fault below ground, and 

 the other connected with the surface strata, the deflection was again con- 

 siderable. I then erected the apparatus in my own house, connecting one 

 end with a rod inserted in the line oi' a fault, at a short depth from the 

 surface, and the othei' with tlie surface strata with the home-made sjal- 

 vannneter I got slight though perceptible deflections, and with the 

 galvanometer which was received fi-om Tokio I have since obtniued 

 deflections quite capable of regi; ation. 



Owing to my own inexperience and the meagreness of the statistics 

 which I have beeir able to collect, it wonld be altogcthei' absurd to givo 

 any opinion, as yet. us to the connection (if any) between the movements 

 of the galvanometer and the outflow of gas in the mine, and I think that 

 it is preferable to cnllect at least one year's statistics before saying any- 

 iliing further on the subject, than to state tho.t, so far as the experiment.s 

 , have progressed, they tend to render me sangnine that such a connection 

 might be established, and .also that I would bo most happy to receive any 

 advice or suggestions on the subject from people more experienced in the 

 .sidoject than myself. 



Tid'^.l Ohserrations, 



With regard to the (observations to be made with a view to establish 

 the connection (if any) between the crushing together of the roof and 

 floor of the mine and the rise and fall of the tide, Mr. Stoddart writes: — • 



