the wind being rolled up afterwards produces the roar of thunder ; or, if both are simultaneous, the lightning moves with a greater velocity towards us and the thunder lags behind, exactly as when persons who are striking blows are observed from a distance.^! A thunderbolt is caused when winds are repeatedl} r ~c6TTected. imprisoned, and violently ignited : or when a part is torn asunder and is more violently expelled downwards, the rending being due to the tact that the compression of the clouds has made the neighbouring parts more dense ; or again it may be due like thunder merely to the expulsion of the imprisoned fire, when this has accumulated and been more violently inflated with wind and has torn the cloud, being unable to withdraw to the adjacent parts because it is continually more and more closely compressed — [generally by some high mountain where thunderbolts mostly fall]. And there are several other ways in which thunderbolts may possibly be produced. Exclusion of myth is the sole condition necessary ; and it will be excluded, if one properly attends to the facts and hence draws inferences to interpret what is obscure. " Fiery whirlwinds are due to the descent of a cloud forced downwards like a pillar by the wind in full force and carried by a gale round and round, while at the same time the outside wind gives the cloud a lateral thrust ; or it may be due to a change of the wind which veers to all points of the compass as a current of air from above helps to force it to move ; or it may be that a strong eddy of winds has been a e.g., as Apelt remarks, when the blows struck by a great hammer on a block of iron are watched from a distance, and it takes some time for the sound to reach one's ear.