THE JURASSIC DEPOSITS WHICH UNDERLIE LONDON. Vat 
The water thus yielded was found by careful trial to rise in a 
tube to an altitude of 49 ft. above the surface and overflow, and a 
suitable pressure-gauge showed that the water rose with a force 
that would cause it to attain to a level of 126 ft. above the surface, 
or to a height of about 130 ft. above Trinity high-water mark. 
[An analysis of the water yielded by the bore-hole when it had 
reached the depth of 1337 ft. was made by Dr. E. Frankland, F.R.S. 
The result of this analysis expressed in parts per 100,000, shows the 
water to be charged with mineral matter to the extent of 104°88 
parts of solid matter in 100,000 parts of water, consisting of upwards 
of 30 parts of chloride of sodium and 57:2 parts of carbonate of soda. 
The water at this depth maintained the soft character found in the 
previous analysis, and was again under two degrees of hardness by 
Clark’s scale. | | 
. The steam-apparatus and tools used in sinking this bore-hole down 
to the depth of 1337 feet were those known as the “ flat-rope system.” 
A heavy boring-bar armed with steel cutters, secured at the end of 
the flat rope, strikes a succession of blows (about 20 a minute), and 
so cuts up the bottom of the bore-hole, the percussive action of the 
boring-bar being produced by a steam-cylinder above the surface of 
the ground. A ratchet-motion fixed to the boring-bar and the 
twist of the rope cause the steel-cutters to rotate whilst the percus- 
Sive process is In operation. By this system excellent samples can 
be obtained, the round cores being produced by the inner edge of the 
steel chisels that radiate from the circumference towards the centre 
of the boring-head, and so cut out a solid portion from the centre of 
the bore-hole as the chisels fall and rotate. Sometimes these round 
cores are brought to the surface jammed between the steel chisels of 
the boring-head, at others they are brought up with the rest of the 
débris which is removed from the bottom of the bore-hole by means 
of a shell-pump, also lowered and raised by the flat rope: the shell- 
pump does valuable work in bringing to the surface, with little loss, 
the softer layers of clay and loam met with between the harder beds. 
From 436 ft. below the surface down to the present depth, cores 
and other samples, every 2 or 3 ft. apart, have been carefully kept 
and labelled as the boring proceeded. 
The size and nature of the cores varies with the diameter of the 
bore-hole and the character of the strata from which they are cut. 
In the Chalk, where the diameter of the hole bored was 167 in., the 
cores are very round and perfect, and about 33 in. in diameter, and 
in some cases 8 or 9 in. in length. 
From the Gault and Lower Greensand, where the diameter of the 
bore-hole was reduced to 134 in., the cores are 24 in. in diameter ; 
and in the Oolitic limestone, where the boring was further reduced 
to 114 in., the cores were found less frequently, and were about 
2 in. across. 
[At the depth of 1334 ft. the boré-hole was reduced to a little 
under 9 in. in diameter, and the rock being very jointed and fissured 
few perfect cores were obtained by the percussive system of boring 
above described. At the depth of 1337 ft. it was found expedient 
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