CONTENTS. 



List ov Plates ix 



Intuoi>l'ctiox xi 



CHAPTER I. 



THEORETICAL fOXSIDERATIOXS REGARDISCi EARTHQUAKE IMOTIOX. 

 A RT. TAOE 



1. Vibrations proceeding from a centre \vii]iin an ehistic siilistance 1 



2. Velocities of Transit '2 



3. Etlet't of boundaries. Reflection and Refraction 3 



4. Example: Case of an EartlKpiake reflected at the surface of a eca 



or lake 4 



5. Reflection and Refractinn at the buiindury of two solid niediiuns ö 



t). Waves (ffifri Dating in or tran<niitte<l inin an aulolrnpii' solid (i 



7. Ert'ect of a stratum in vedu]plicatiuL; waves (i 



>i. Ert'ect of obstacles. Kartliijuake Shadows and Diflraction 8 



9. Energy of Vibrations y 



1(1. Effect of imperfect ela.sticity 10 



11. Movements of a ]iarticle during an Earthquake H 



12. Miitiiiii at the surface of the soil ilue to a uiu'tnal wave VI 



l.'J. Priliininary Statement of the Residls (if ( )bservalions i;! 



CII.M'TEU II. 



I.NHTUlTjIES'iy lul: ()H-i|;itVIN(i lloltlZo.NIAI. .MOV KM i: XT: — 

 Till-: IIORiy.O.NTAI. l-KNDII.rM MKIHMuiJItAI'lI. 



14. .M«'a.>urenieiit of cnrthiiuaki' iiiiili"pii> by rcl'cri'iicc tu u Steady i'ninl... II 



1Ö. KiiK-lic condition yielding II Sicaily I'liinl 14 



!•!. HtAtic condition retpiisite for a Sleaily Piiint 15 



17. Horizontal Pendulum Sc-isinometer 16 



IH. Friction l-'mir. Iiwrea-'i' of Ktli'ciivc Tncrlia by the ii« of a scronrl 



nui'-s pivoltcd nil the first at the Stcaily Line 17 



lit. Determination of the EH'cclive Iiierli« and Stewly I^iiie 18 



