88 The Rev. S. Earnshaw on the Velocity 



In the spring of 1851, when I was living in the small village 

 of Conisborough about five miles from Doncaster, there occurred, 

 one Sunday evening about 5 o'clock, a thunder-storm which lasted 

 about half an hour. It was not different from other thunder- 

 storms, except that it was terminated by a flash of lightning of 

 great vividness, which was instantly (i. e. without any appreciable 

 interval between) followed by an awful crash, that seemed as if 

 by atmospheric concussion alone it would crush the cottages to 

 ruins. Every one in the village, as I found afterwards, had felt 

 at the moment of the crash, as I felt myself, that the electric 

 fluid had certainly fallen somewhere in the village. Indeed it 

 seemed impossible for any one to think otherwise than that his 

 neighbour's cottage had been struck, and his own had had a 

 narrow escape. But, to the surprise of everybody, it turned out 

 that no damage had been done in the village, but that that flash 

 of lightning had killed three sheep, knocked down a cow, and 

 injured the milkmaid who happened to be milking the cow, at a 

 distance of more than a mile from the village. I was at that 

 time under a physician's orders not to think about anything, 

 but I remember thinking that it was very singular the lightning 

 should fall at such a distance, when I should have expected it, 

 from the received theory of sound, to fall in the village. Professor 

 Montigny's memoir records similar, and yet more striking 

 instances, which have come to his knowledge or been observed 

 by himself. In one of them the report of a thunder-clap reached 

 him after an interval of 2 seconds, which according to theory 

 should have occupied more than 15 seconds. As he well 

 remarks, the difference in this instance is too great to be accounted 

 for by the agency of wind, or errors of observation; besides 

 which, his observation was confirmed by an independent ob- 

 server, the cure of a parish a few miles off, who observed the 

 same flash and estimated the interval that elapsed before the 

 report reached him at 2 seconds, though according to theory it 

 should have been nearly 15 seconds, the two observers and the 

 point struck by the electric fluid being nearly equidistant from 

 one another. Other cases, less striking perhaps, but quite 

 agreeing with this, are recorded in the memoir ; and after reading 

 them and remembering my own experience, I cannot but consider 

 this a subject worthy of the attention of observers. And if it 

 shall seem good to them to record their observations in cases 

 where, from some noticeable peculiarity, the point struck by a 

 particular flash can be identified, I strongly suspect it will soon 

 be established as a law of nature, that the sound of a thunder-clap 

 is propagated with far greater rapidity than ordinary sounds. 

 We shall presently see what light theory throws upon this point. 



9. The velocity of sound has been determined in the last 



