THE JURASSIC DEPOSITS WHICH UNDERLIE LONDON. 725 
Down to 434 ft. the writer of this notice was in no way 
connected with the carrying out of the work; Messrs. Russ and 
Minns being the engineers under whose direction the well and bore- 
hole to the depth before stated were executed. Samples of the 
Tertiaries passed through were kept, and can be inspected at the office 
of the Waterworks, Water Lane, Richmond. 
The water yielded by the above well and bore-hole (about 160 
gallons a minute) is mainly derived from the Tertiaries, and in its 
normal condition rises + or 5 ft. above the surface; at present, 
however, the level of the water is always depressed about 130 ft. 
by pumping. 
In 1881, a further supply of water for the town being needed, 
the Richmond Vestry, acting upon the advice of the writer’s father, 
Mr. 8. C. Homersham, M.Inst.C.E., determined to carry the bore- 
hole to a much greater depth; a contract was accordingly entered 
into to execute the necessary preliminary works, and to deepen 
the bore-hole by steam-machinery. The existing bore-hole was 
first enlarged and straightened to enable a line of cast-iron pipes 
with an internal diameter of 164 in., having the lower end driven 
water-tight into the Chalk at a depth of 488 ft., to be carried up 
to the surface.. An annular space between the circumference of 
the bore-hole and the outside of the line of iron pipes was left, of 
sufficient capacity to allow any water yielded from this bore to rise 
into the well in an uncontaminated state for the supply of the town 
during the time the bore-hole was being deepened. From the in- 
side, and below the bottom of this line of pipes, a bore-hole 163 in. 
diam. was commenced in January 1882. The enlarging of the 
original bore-hole, and the subsequent deepening, proved the chalk 
to contain regular layers of flint down to the depth of 502 ft., as 
shown in the section (fig. 1, p. 744). Hard grey chalk was met with 
at 580 ft. 6 in., and chalk marl nt 820 ft., the latter oe to be 
about 104 ft. thick. 
The total thickness of the Chalk was thus 671 ft.; and below 
the depth (434 ft.) where the new boring commenced, it failed to 
yield any water. 
The Upper Greensand was next encountered, and proved to be 
only 16 ft. thick, ranging between the depths of 924 and 940 ft. 
This bed was of a close and compact nature, and did not yield any 
water. 
The Gault clay, 201 ft. 6 in. thick, was next successfully pierced, 
a thin bed of phosphatic nodules (of the type usually underlying 
the Gault stratum) being met with at its base at the depth of 
1141 ft. 6in. from the surface. A bed, which is probably of Neo- 
comian age, was next reached ; but further boring proved this series 
to be but meagrely represented by a bed only 10 ft. in thickness, 
unfavourable to the percolation of water; the samples and cores 
obtained showing it to be of a sandy and glauconitic nature, the 
harder portion much resembling Kentish Rag. 
Another thin layer of phosphatic nodules was passed through at 
1151 ft. 6 in., when a bed, at its first appearance of an abnormal 
OeueGes. Nox k60: 3 
