39 



excited, tell him, we have more tales of wonder in store ; of flocks 

 of cattle, of large companies of men, and of even whole cities, with 

 their inhabitants, converted to stone*. I could supply him, from- 

 a comparatively modern author, with an account of a troop of Spa- 

 nish horsemen, who thus underwent the process of petrifaction -f ; 

 and with a very seriously attested relation of a petrified child, which 

 was shewn at Paris, and which was, occasionally, used by its pos- 

 sessor as a whet-stone ! 



Yours. 



LETTER V. 



FORM OF THE EARTH^S SURFACE... .MOUNTAINS.. ..STRATA, ...WIS- 

 DOM MANIFESTED IN THEIR DISPOSITION. ...DIFFERENT KINDS 

 OF EARTHS. ...ALUMINE ; FORMING CLAY, LITHOMA'RGA* 



c.... SILICA; FORMING ROCK CRYSTALS, CALCEDONY, 

 &C....LIME ; FORMING LIME-STONE, CHALK, TUFA, MARBLE, &C. 

 ....MAGNESIA; FORMING STEATITES, ASBESTOS, SERPENTINED 

 &C....SULPHURETS, PYRITES, OR MARCASITES. 



J MUST intrude on your patience, with one letter more of intftK 

 ductory matter ; it being necessary, before we speak of secondary 

 fossils themselves, to give a cursory account of the matries 9 in which 

 they are found : and of the substances, of which both they, and the 

 fossils themselves, are formed. 



* Aventini, lib. vii. Annal. Boiorum. Purchas's Pilgrimage* jfc 24fv 

 t Jos. Acosta, lib. iii cap. 9. t Vide Helmont de Lithiasi 



