1894.] On the Leicester Earthquake of Auyust 4, 1893. 19 



and tri-nitro-cellulose in proportion corresponding to the nitrogen as 

 found by analysis. 



The equation for Experiment C may be taken as follows : 



50 per cent. 50 per cent, nitro-cellulose 



nitro-glycerin. (N = 12'3 per cent.). 



6[C 3 H 5 (N0 3 )3] +2[C 6 H 7 (N0 3 ) i A] +3[C.H 8 (N0 8 ),O,] = 



25CO a +28CO+8H+30N+30H 3 O. 



The composition of this explosive, calculated from the foregoing 

 formula and found by analysis, is as follows : 



100-0 100-07 



These are some of the principal features noticeable in a preliminary 

 survey of these experiments. We are continuing our investigations 

 on the lines indicated in the paper, and are especially endeavouring 

 to measure the actual temperature of explosion under varying con- 

 ditions, and it is hoped that the results obtained will throw some 

 light on the chemical and physical properties of many gases at b igh 

 temperatures and under considerable pressures, and, at the same 

 time, be useful in the practical application of explosives . 



IV. " On the Leicester Earthquake of August 4, 1893." By 

 CHARLES DAVISON, M.A., Mathematical Master at King 

 Edward's High School, Birmingham. Communicated by 

 Professor J. H. PoYNTiNG, F.R.S. Received February 28, 

 1894. 



(Abstract.) 







On August 4, 1893, at 6.41 P.M., an earthquake of intensity nearly 

 equal to 6 (according to the Rossi-Forel scale) was felt over the 

 whole of Leicestershire and Rutland and in parts of all the adjoining 

 counties. The disturbed area was 58 miles long, 46 miles broad, and 

 contained an area of about 2066 square miles. The direction of the 

 longer axis (about W. 40 N. and E. 40 S.) and the relative position 

 of the isoseismal lines show that the originating fault, if the earth- 

 quake were due to fault- slipping, must run in about the direction indi- 

 cated, passing between Woodhouse Eaves and Markfield, and heading 



C 2 



