t 2 +2 ] 
for the purpofe of conveying air into an adjoining 
' work, called Mearn’s coal-pit ; but when this fhaft 
was finiftied, the water that flowed in from the fides, 
and which at firft was taken up by buckets, greatly 
incommoded the under-works ; and therefore, to 
prevent this inconvenience, the miners, at about the 
depth of ten fathom, and juft below the place where 
the water broke in, affixed to the four fides of the pit 
fome wooden ffioots (as reprefented at Fig. 2.), about 
four or five inches wide, and as many deep; all of them 
a little inclined towards one corner, where was a 
hollow perpendicular pipe or trunk of elm, nearly a 
long fquare (as reprefented at A), being about feven 
inches and an half one way, and four inches and an 
half the other; and through this the water, that fell 
into the lateral ffioots, was conveyed down to the 
level (or pafiage out) ; which being about feven fa- 
thoms lower than the ffioots, the hollow perpendi- 
cular trunk was about fourteen yards in length. 
This trunk having been thus fixed up, in the latter 
end of the year 1766, was in about three years time, 
or rather lefs, found to be much obftru&ed, and 
flopped up; fo that, in Auguft 1769, the miners 
were obliged to take it up : and then, on examining 
it, and taking it to pieces, they found the whole 
cavity, from one end to the other, nearly filled with 
a fort of fparry incruftation, fomewhat fofter than 
marble, but harder than alabafter, and which there- 
fore I (hall venture to call a fpecies of marble. And 
the fpecimen now laid before the Society, and repre- 
fented by the drawing (Fig. 1.), and alfo another 
•fpecimen of the like fort, prefented to the Society, 
4 ^are 
