292 



s. SEKIYA AND F. ÖMORT. 



This was the niaximnni acceloi'alion in tlie upper districts of Tokyo 

 where tlio u'roiind is composed of hard loamy soil ; in the lower 

 districts, where the ütoutkI is soft and marshy, it nearly reached 

 the value of 1,000 mm. ])er sec ycr sec. This latter has l)een cal- 

 culated from a similar rcmrd oiven l)y anotlier T>arixe ]\rotion Seismo 

 gra])!! set up in the lower ])nrt of tlie rity. Xow tlie maximuTu a'-œlera- 

 tion is the (juantitv which measures the destructive power of earth- 

 quake motion, and it may tlierefore he inferred tliat wluMiever it reaches 

 the aho\e values, chimnevs will he o-reatlv damao'ed and hiiildinii's 

 affected ns on tliis occasion. Tor the Mino-Owari ({reat Earthrpiake 

 of 1801, one of us has cah-nlaled, from ohscrNations of numerous 

 overturned and Iractured l)odies. the maximum ar-cclci-alion of (earth- 

 quake motion in the meizoseismal district to have l)een from o.OOO 

 mm. up to nearly 11). ()()() mm. j'cr sec. ]>er ^co.'^ These i-esu Its are 

 pr(jhal)Iy tlie iirst numerical estimation that has heen made of the 

 destructi\e ])0a\('1' of u'reat ('arth(|uakes. 



]>iiir(fii)n. of ihr /\(irlliqinil-<'. Tlie sliakin^ti' lastefl ahout 4 miimtes 

 and .')0 seconds. 



1. See l'\ Oiiiori : Tulilt- of tin- orcrtiiniiiifi (icccJeration, etc. Scisinological Jrmr. .lajian, 

 Vol. I, p. 143. 



