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out on the Side of the Hill with aconfiderable Force, 
could not fail to form Caverns in the Side of the 
Mountain, and to change its Current as the Pafiages 
became choaked up with the tophaceous Matter : 
And as I found vaft Numbers of Molecule like Grains 
of Sand in the Chinks where Water patted, thefe being 
wattied off might ferve for Nuclei to the Pifohthi, and 
being kept in continual Motion by the Vortex or 
Whirling of the Water, would acquire a globular 
Figure, and by receiving new fheliy Coats, from 
time to time, would increafe in Bulk, fo long as 
they were fuftaincd, and whirled about in the W ater. 
And as in this Cafe fome would be precipitated fooner, 
and others later, a Difference in Size mutt confe- 
quently happen, and their Arrangement mutt be ac- 
cording to their Proportion of Surface and Gravity-, 
till the Place becoming full of fuch Matter, the 
Water was obliged to feek out a new Paflage. At 
the Formation of this Kind of Tophus in the 
Caverns, fome intervening Accidents from the Mo- 
tion of the Medium, the Influence of the Air, and 
other concurring Caufes, have fometimes fo far 
prevented a compact and firm Conjun&ion of the 
component Particles, that in feveral Places it feems 
in a decaying State ; and is even foft as Clay. In 
the Air indeed it grows again fomewhat harder, but 
then it is porous and light : And they call it Sproudle 
Sand. The Inhabitants of a Houfc near the Church 
have a Hollow, out of which they take this, and 
fell it for the fcouring and polifhing of Silver, &c. 
In this Hollow it is very warm and fuffocating, efpe- 
cialiy in rainy Weather, and then there rifes from 
it a ftrong Vapour. 
On 
