11 Professors Perry and Ayrton on a neglected Principle 

 Let the springs be strong, so that 



and let 



* %\ 

 then, determining the values of the constants, we find 

 #- -e- b '" tk x 0-00458 A cos (9*62 kt + 0-5142) 

 -0-00814 A cos (H-0'0917) 

 + 0-01218 A cos (M 7^-0-1096), 

 the curve corresponding with which is shown by the thick 

 white line i i i in fig. 3, the thin line 8 S S being 



t t'=- e -^ x 0-00458 A cos (9-62H + 0-5142), 

 the thin line rjrjr) 



« = -0-00814 A cos (fa-0-0917), 

 and the thin line 



= 0-01218 A 008(0^-0-1096). 



This curve (i i i) is magnified so that the greatest amplitude 

 is nearly the same as the greatest amplitude in the real earth- 

 quake motion. 



If the springs remain as before, but if there be no friction, 

 then, determining the constants, we find 



0= -0-00408 A cos (11-i kt) 



- 0-00816 A cos (kt!) 



+ 0-01224 A cos (1-2 &*)• 

 If the earthquake be represented by the same equation as 

 before, and if 



and 



then equation (3) becomes 



, 7;= - e -l u x 0-071831 A cos (2-551* + 0-78015) 



-0-11704 A cos O-0-35896) 



+ 0-17877 A cos (0-^-0-45408); 



the curve corresponding with which is shown by the thick 

 white line vvv (fig. 4), the thin line kkk being 



#= -e-3*' x 0-071831 A cos (2-55 fa + 0-78015), 



the thin line \W 



x= -0-1 1704 A cos (7^-0-35896), 



