1410. The explosion, if high in the air and remote from us, will do no mischief, but when near, it may; and it has, in a thousand instances, destroyed trees, animals, &c. This proximity, or small distance, may be estimated nearly by the interval of time between seeing the flash of lightning, and hearing the report of the thunder, reckoning the distance after the rate of 1142 feet to a second of time, or four seconds and a half to the mile. Dr. Wallis observes, that commonly the difference between the two is about seven seconds, which, at the rate above mentioned, gives the distance almost two miles: but sometimes it comes in a second or two, which argues the explosion very near to us, and even among us; and in such cases, the doctor assures us, he has sometimes foretold the mischiefs that happened.
