FREESTONE. 21 



the bank, in a darkish sort of marl ; and are usually very- 

 small and soft ; but in Clay's Pond, a little farther on, at 

 the end of the pit, where the soil is dug out for manure, I 

 have occasionally observed them of large dimensions, perhaps 

 fourteen or sixteen inches in diameter. But as these did 

 not consist of firm stone, but were formed of a kind of terra 

 lapidosa, or hardened clay, as soon as they were exposed to 

 the rains and frost, they mouldered away. These seemed as 

 if they were a very recent production. In the chalk-pit, at 

 the north-west end of the Hanger, large nautili are some- 

 times observed. 



In the very thickest strata of our freestone, and at con- 

 siderable depths, well diggers often find large scallops, or 

 pectines, having both shells deeply striated, and ridged and 

 furrowed alternately. They are highly impregnated with, if 

 not wholly composed of, the stone of the quarry. 



LETTER IV. 



TO THE SAME. 



As, in last letter, the freestone of this place has been only 

 mentioned incidentally, I shall here become more particular. 

 This stone is in great request for hearth-stones, and the 

 beds of ovens.; and in lining of lime-kilns it turns to good 

 account ; for the workmen use sandy loam instead of mortar ; 

 the sand of which fluxes,* and runs, by the intense heat, and 

 so cases over the whole face of the kiln with a strong 

 vitrified coat like glass, that it is well preserved from 

 injuries of weather, and endures thirty or forty years. 

 "When chiselled smooth, it makes elegant fronts for houses, 

 equal in colour and grain to the Bath stone ; and superior 

 in one respect, that, when seasoned, it does not scale. 

 Decent chimney-pieces are worked from it, of much closer 

 and finer grain than Portland ; and rooms are floored with 



* There may, probably, be also in the chalk itself, that is burnt for lime 

 a proportion of sand ; for few chalks are so pure as to have none. 



