18 



Roe-stone. It is used for building in many places : some 

 of the colleges at Cambridge are built with it. The same 

 uniform appearance extends to very large masses ; and al- 

 though a sound, strong and durable stone in the mass, very 

 little pieces may be crumbled to grains by the fingers. The 

 masons use a common carpenters saw in working it : the 

 little rounded particles being easily detached, it passes readily 

 through it. They sometimes have a little dusty or solid 

 nucleus, coated concentrically; at other times are hollow. 

 In the next county, Northamptonshire, there is a stone 

 called by the masons Barneck, greatly resembling this, but 

 coarser, containing shells, &c. Col. Walford found a stone 

 of a similar nature with larger grains (which approaches the 

 oviform limeftone of Kirwan, v. i. 91), at Birdbrook, Essex, 

 mingled with shells, which has sometimes sufficient clay or 

 argil to be called a marie. 



Middle figure. Bath-stone, frequently contains the same 

 concretions, but more decomposed, and a matrix surround- 

 ing them, somewhat confusedly crystallized, forming little 

 hollows : many species of shells, encrini, &c. are found in 

 it ; sometimes however so comminuted as to be quite 

 indistinct. I picked up a piece of stone at Burford in 

 Oxfordshire, which is of a reddish brick colour, with the 

 hollows very distinct, giving it a volcanic or cindery appear- 

 ance. With difficulty very small pieces crumble between 

 the fingers. 



Lower figure. Portland-stone, nearly like the Bath-stone. 

 The best sort is more compact, and whiter : there are many 



