10 



DE. CHARLES DAVISON ON THE 



[Feb. 1906, 



figures agree closely with those obtained for the Derby earthquake 

 of 1904. 1 



The variation in the nature of the sound with the distance from 

 the epicentres is shown in the following table (I), in which the figures 

 are percentages of comparison to the different types for each of the 

 districts mentioned : — 



Table I. 



03 



'4 

 > 



'5J 



cS 



Pm 



a 



en 



T3 



Loads of stones 

 falling. 



C5 

 <V 



.— i O 

 I* 



°5a 



O 



'ft 



^ Miscellaneous. 



Within isoseismal 7 



34 



38 



11 



3 



1 



11 



Between isos. 7 and 6 . . . 



39 



29 



' 11 



8 



4 



8 



1 



„ 6 „ 5... 



48 • 



26 



11 



3 



5 



5 



3 



., 5 ., 4 ... 



41 



31 



17 



1 



2 



5 



3 



» 4 „ 3... 



46 



16 



38 











Thus, with increase of distance from the epicentres, there is a 

 marked diminution in the proportion of comparison to sounds of an 

 abrupt or irregular character, and a corresponding increase in those 

 of a smooth or monotonous type. 



Time-Relations of the Sound and Shock. 



In Table II (below), the letters p, c, and / indicate the number of 

 records per cent, in which each of the principal epochs of the sound 

 (namely, the beginning, the epoch of maximum intensity, and the 

 end) preceded, coincided with, or followed, the corresponding epoch 

 of the shock ; the letters g, e, and I show the number of records 

 per cent, in which the duration of the sound was greater than, equal 

 to, or less than, that of the shock. 



Table II. 



Beginning. 



ErocH of 

 Max. Int. 



End. 



Relative 

 Duration. 



P 



c 



/ 



V 



c 



I 



62 



78 



64 

 62 



/ 



18 



8 



11 



12 



P 

 16 



10 

 11 

 26 



12 



21 



18 



c 



67 



41 



47 

 32 



46 



55 

 51 



/ 



17 



49 

 42 

 42 



42 



24 



31 



9 



82 



76 

 71 

 65 



74 



46 

 62 



e 



18 



18 

 20 

 30 



20 



46 

 31 



I 



... 



6 

 9 

 5 



6 



9 



7 



Within isoseismal 7 



Between isoseismals 7 and 6 . 

 6 „ 5. 

 5 „ 4. 



Whole sound-area 



Do. for Derby earthq. of 1903 

 1904 



84 



76 



68 

 68 



73 



65 



- 



15 

 20 

 23 



18 



37 



29 



1 



9 

 12 



9 



9 



7 

 6 



... 



27 

 31 

 11 



24 



30 



1 Quart. Journ. Geol. Soc. vol. lxi (1905) p. 14. 



