BRONTIÆ, or Thunder-stones, in Natural History. Brontium flory. These were supposed, according to the opinion of many philosophers, to have only an imaginary existence.

But of late years the attention of naturalists has been much directed to stones that have fallen from the clouds. The fact seems to be sufficiently established; but whether the stones are formed in the atmosphere during the thunder storm which generally accompanies their fall, are ejected from a volcano, or projected, as some suppose, from the moon, there is great difference of opinion.