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name, and laying near the high road, between the 
towns’ of St. Ives and Somerfham, in the county of 
Huntingdon, about three miles diftance from St. Ives. 
This heath was formerly covered by part of the 
royai forefts cut down in the reigns of Henry II. HI. 
or of Edward I. and now ferves only for the grazing 
of fheep. 
The different ftrata of the earth on this heath are, 
immediately under the fwerd, firft, about fix inches 
depth of mould, or arable, then different ftrata of 
clay, each ftratum about ten or twelve inches deep, 
growing darker from a yellowifh or grey color, to a 
dark blue golt the deeper it lies. At about feven feet 
deep is found a bed of gravel, out of which the wa- 
ter fprings forth very clear. This ftratum of gravel is 
about twelve or fourteen inches thick, furrounded 
with a bed of a very dark blue golt, befet with large 
quantities of felenites, which have fhot in it, and 
are furrounded with lb me fine yellow clay flick- 
ing to them. 
The water, flowing from this fpring,, which is 
perennial, but runs more or lefs according to the 
different fcafons, is received from the bed of gravel 
by three fmall brick channels, about two feet long, 
which meet in one of about fix inches fquare. This 
channel which is near twenty feet in length, conveys 
the water to a bafon alfo of brick, and about two feet 
fquare. The channel and bafon were made about 
40 years ago under the direction of the late Rev. Dr. 
Knight j were opened and cleaned in the years 1755 
and 1759, when I directed the workmen to new 
lay the bricks of the channel in fome of the ftiff blue 
clay, inftead of lime-mortar, that the water might 
be 
