r 22 9 ] 
Mr. Drury, whom 1 (hall have occafion to men- 
tion, found in a ftone of the Caufeway a rough peb- 
ble in the fhape of an egg, about three quarters of 
an inch long, and above an inch thick ; and when it 
was polifh'd, it proved to be a white cornelian. They 
are from three tides to nine tides, frequently encom- 
pafied with as many ftones as there are tides ; but 
many of them have a narrow fide, which has no 
ftone to it, but is filled up with a piece or pieces of 
ftone, that fhall be further explain’d ; which pieces, 
when the ft ones are mov’d, commonly feparate, and 
break off. Some ldones have two, or three, or more, 
of thefe tides: fo that it is poftible, a ftone, that 
has any number of ftones round it, may have dou- 
ble the number of tides : tho’ I faw none, that I had 
reafon to think were of this kind, except fome, that 
had probably only three ftones round them j being 
hexagons with three broad tides, and three very nar- 
row tides. 
Whatever the outward figure of the ftone is, the 
concavity or convexity is either circular, or part of a 
circle ; confequently, as the tides of the pillars are 
plain, the part between the infide circle and the out- 
ward figure muft either be fill’d up (as it is feen) by 
ftone, which fometimes feparates, as mention’d above, 
and as will be further explain d; or by the matter 
preffed up from the tides, as will be more plainly 
defcribed. In the former cafe, when the end is con~ 
vex, this ftcne often comes off all round at thejoint, 
and leaves the convex end as pa>t of a fphere, and 
the concave as a mould fitting to it. 
I have fome ftones exactly like a hexagon cut in 
two, which might be part of a hexagon pillar lplit 
for 
