24 HISTORY OF COLCHESTER CORPORATION WATER WORKS.
above high water mark, and continued at that level for nine
years up to 1859. On enquiring of Mr. Bruff in 1889 as to what
high water mark he referred to, he replied "that the circum-
stances were too remote for his recollection, that it might mean
H.W.M. at the Hythe (tidal river) or the Mill Head at North
Bridge."
On the 2nd October 1888, I levelled the rest level and found
it to be 7.66 above O.D. On the 12th March 1902, it was
278 below O.D., or a difference of 10.44 feet, but it must not
be lost sight of that the years 1900, 1 and 2 were very dry years.
On the 23rd March last, the rest level was 1.72 feet above O.D.,
or 5.94 feet lower than in 1888, but 4.5 feet higher than in 1902.
As I have before stated, there are many instances and examples
of the Roman engineers having sunk wells to obtain water from
the gravel beds underlying their camps and stations, but I am
not aware there are any examples in existence, or that they
understood the art of sinking a well or bore hole, to obtain a
supply of water from a permeable formation underlying an
impermeable one where the gathering ground or outcrop was at a
higher elevation, and situate at a considerable distance from the
site of the proposed well.
Mr. Bruff's well and bore holes are still in existence, and
assisted in supplying the town up till 1890, when they were put
entirely out of use on account of the new well adjoining being
sunk to a much greater depth, the water level being depressed
when pumping below the bottom of the old well.
As soon as the Corporation came into possession of the water
works in 1880, they immediately put down another well 30 feet
(centre to centre) away from Mr. Bruff's old well, but only four
feet deeper; they, however, carried an 18" bore hole down to a
total depth of 384 feet. Although they obtained very little
more water by this operation on account of not being able to
depress the pumping level with the then existing machinery,
nevertheless this 18" bore hole turned out to be a very valuable
asset, as it formed the nucleus of my new scheme in 1888. The
bore evidently penetrated a large and open fissure in the chalk,
low down in the bore hole, as on making careful and systematic
pumping experiments the bore hole was found to yield water
very freely.
In 1887 I advised the Corporation as to how they could