I 



PREFACE. 



Tile t'dlldwiiiii- Memoir has ütowi) mil of wdi'k \vlii<'li, witli tlic ^I'liiToiis 

 iissistanoe of the President of the Univeivit^', I began in the winter of 1879-80, 

 and wliich lias been eontinued until now. The ereetion of instrnnients adapted 

 to the absolute ineasiirt'ini'iit ol' i'arthi|Uake niotions was (|ni<'kly followed by the 

 registration of iiiimcroiH rartlniiiai^rs. Tiiesr occur in Tokio with a fi'ci|ucnc\' 

 wliieh gives resident stnilents of seismic jihenomena an advantage ditücidt to 

 overrate; and it is therefore no wonder that the instrumental side of Seismology 

 has had its most considerable develo]tment in Japan. 



The e.ssay is cliietly an accimnt of my own iiLStruments, method.s, and results; 

 but, with the view of making it as coiii])lctc a ti'oatisc on Earthquake Measiwe- 

 meiit as the present state ol' the subject allows, I have included many notices of 

 apparatus designed by other eonteniporarv workers, as well as of older forms. 

 lu referring to the wori; of other ofeervers, I have endeavoured in every ease to 

 give the fullest credit for novelty, where there is novelty. It may be addetl, 

 with respect to recent seisniological work a<-complished in Jajian, that the five 

 volumes of the .Seismologieal Society's Tran.<aetions now published contain 

 original aceonnts of most of the instrinnents deseribed in this paper, and should 

 be refiTred to by any one interested in the historv i:>f the sul>)eet. 



My special acknowledgments are due to Mr. Kato, the President of the 

 University, to Mr. Hamao, tiie former N'icc-l'resideiit, and to ^Ir. Hattori, the 

 present holder of that otHee, for providing me with the means of establishing a 

 S<'ismological Observatory. The frefpiency and sneoe.ss with whieh earthquakes 

 have Ix-en rworded are in great measure owing to the attention bestowi'd on the 

 instruments by my assistant, Mr. K. Sekiya, in whose care I am happy to be 

 able to leave the apparatus on my approaching departure from .bi|ian. To 

 Mr. Fuknda I am indelited ibr the preparation of most of the J'latcs which give 

 illustrations of the seismographs I have used. Plates XII-XX aiv exact copies 

 of actual carlli<|uakc records, cxccuIikI with a fidcliiv whieli docs great I'reilit 

 to the draUi.dit-m:ni, Mr. Sii/.nki. 



J. A. EWIXt;. 





The Uxi\'EitsiTY, Tokio, 

 M,ni -liul, 1H«;{. 



