﻿16 



DE. CHARLES DAVISON ON THE 



[Feb. 1905, 



and contains 425 square miles. The distance between the two 

 isoseismals is 6 miles on the north-west, and 4| miles on the 

 south-east, side. The shock and sound were also observed, though 

 very faintly, at Derby, 1| miles south-east of the isoseismal 3, and 

 at Leek, 4 j miles west of the same curve. 



Map illustrating the area affected by tie aftershock 

 of July 3rd, 1904. 



mal 3. 



°.Derby 



Scale of Miles 

 246 



The shock is uniformly described as a continuous series of rapid 

 vibrations, the average of four estimates of its duration being 

 3| seconds. The sound was heard by 96 per cent, of the 

 observers, and was compared to passing vehicles in 28 per cent, 

 of the records, to thunder in 39 per cent., to wind in 11, to the 

 fall of a load of stones in 6, and to explosions in 17 per cent. 

 The beginning of the sound either preceded or coincided with 

 that of the shock; the end of the sound generally coincided 

 with that of the shock. 



