﻿Yol. 6 1.] LEICESTER EAETHOJJAKES OE 1893 AND 1904. 5 



Quorn, and Slawston) the first part is invariably described as the 

 stronger. The interval between the parts is in every case estimated 

 at 2 seconds. 



The boundary of the area within which the double shock was 

 felt is represented on the map (p. 4) by a broken line. It is 

 29 miles long, 20g miles wide, and includes an area of 464 square 

 miles ; its axis is nearly parallel to those of the isoseismal lines, 

 running from K 40° W. to S. 40° E. The centre of the curve 

 is about half-a-mile south-west of Houghton- on- the-Hill, in lat. 

 52° 37-1' JS"., long. 1° 0-8' W., or 2J miles north-north-west of the 

 centre of the isoseismal 5. As the boundary of the double-shock 

 area is close to the isoseismal 5 towards the south and east, and to 

 the isoseismal 4 towards the north and west, it cannot coincide 

 with an isoseismal line corresponding to an intensity between 5 

 and 4. Thus, while the dotted line represents the boundary of the 

 disturbed area of the first part of the shock, and the broken line 

 that of the second part, it is evident that the foci of the two parts 

 were not coincident, but, at the same time, were not completely 

 detached. The earthquake may therefore be described as a double 

 one, rather than as a twin-earthquake. 



Sound-Phenomena. 



As already mentioned, the boundary of the sound-area (repre- 

 sented by the dotted line in the map, p. 4) coincides approximately 

 with that of the disturbed area. The district is too small, and the 

 number of records insufficient, for the construction of isacoustic 

 lines ; but it is evident, from the descriptions given, that the sound 

 was unusually loud within a central area bounded approximately by 

 the isoseismal 5, which is very nearly concentric with the boundary 

 of the sound-area. The sound was, however, heard by nearly all 

 observers close up to the latter boundary ; for the percentage of 

 audibility was 97 over the whole area, 98 within the isoseismal 5, 

 96 between the isoseismals 5 and 4, and 93 between the isoseismal 4 

 and the boundary of the sound-area. 



The sound was compared to passing traction-engines, etc., in 

 62 per cent, of the records, to thunder in 17 per cent., wind in 4, 

 loads of stone falling in 7, the fall of a heavy body in 5, explo- 

 sions in 4, and to miscellaneous sounds in 1 per cent. There is the 

 usual tendency towards smoothness and monotony in the sound 

 with increasing distance from the origin. Within the isoseismal 5, 

 the percentage of comparisons to passing traction-engines, etc., 

 is 52, 71 between the isoseismals 5 and 4, and 76 between the 

 isoseismal 4 and the boundary of the sound-area. For thunder, 

 the corresponding percentages are 20, 14, and 14. 



In the following table (p. 6), the figures in the columns headed p, c, 

 and / indicate the number of records per cent, in which the be- 

 ginning or end of the sound preceded, coincided with, or followed, 

 the corresponding epoch of the shock ; those in the columns headed 

 g, e, and Z indicate the number of records per cent, in which the 



