399 



on the broad stone pavements, whenever he came just under any of 

 the sign-irons, his cane gave a different sound, and occasioned a 

 different kind of resistance to the hand, from what it did elsewhere; 

 and, attending more particularly to this circumstance, he found, 

 that every where, under the drip of those irons, the stones had ac- 

 quired a greater degree of solidity, and a wonderful hardness, so as 

 to resist any ordinary tool ; and gave, when struck upon, a metallic 

 sound : and this fact, by repeated observations, he was at length 

 most thoroughly convinced of. This observation of the Doctor's 

 was illustrated by some experiments, in which he ascertained, that, 

 by thus washing frequently pieces of Portland-stone with water im- 

 pregnated with rusty iron, they acquired a very sensible degree of 

 the hardness here described, and on being struck gave the metallic 

 sound. Part of a horse-shoe was seen by the Doctor, on the sea- 

 coast, near Scarborough, incrusted with sea-sand ; and, although 

 the sand was but little tinctured with an ochry colour from the iron, 

 it had acquired the hardness of common grit-stone/' 



Part of a ladder, with some of the steps, which Mr. Baillou, of 

 Florence, presented to the Emperor, and which was placed in the 

 Imperial Museum at Vienna, was most probably merely an incrus- 

 tation ; similar incrustations of ladders, &c. frequently occurring 

 at the incrustating springs in this kingdom : and Italy, from whence 

 it appears this cabinet specimen was sent, as we have already seen, 

 abounds with waters possessing this quality. Several authors relate 

 that formerly the handles of hatches, &c. were found in a petrified 

 state. But it should be considered, that formerly, also, the arrow- 

 heads and stone hatchets of the aborigines of some parts of Ger- 

 many, not very dissimilar from those we now receive from the South 

 Seas, were regarded as thunderbolts. Thus Lachmund says, the 

 names of CERAUNIA, Ceraunius Lapis, Donnerstein, and Donnerkeil, 

 were given to those stones which had fallen from the clouds at the 

 time of thunder, and which resemble hammers, hatchets, wedges, &c. 



