Overflowing Well at Chiswick. 71 
rods used in boring were lowered into, and raised from, the well. 
These rods were of tough iron, about an inch and a half square, 
and ten feet long ; the ends of each screwing on to, or unscrewing 
from, the top of the next, as they were lowered into, or raised 
from, the hole. The instruments fixed as occasion required to the 
lowest extremity of the series of rods when in action, were augers 
of various dimensions for boring, steel chisels for punching, and 
a hollow iron cylinder, (called a shell,) fitted with a valve at its 
lower end, for bringing up soft mud. The rods, when an auger 
was attached to them, were turned round by means of moveable 
arms or dogs, which were made to lay hold of the part of the 
uppermost rod at the top of the hole; the auger being thus 
forced through the stratum of clay or sand, was drawn up as soon 
as its cavity was filled with the substance it had loosened. The 
chisels were employed for punching through stones, hard sub- 
stances, or hard chalk ; the rods, when these were attached, were 
moved by means of a powerful beam acting as a lever, and worked 
by four men. 
The water is discharged at the surface of the ground after the 
rate of six gallons per minute, and is capable of being carried 
20 feet above the ground level; and even then supplies a copious 
stream. The well is lined for the first 186 feet with cast-iron 
pipes, with a three-inch bore, jointed by means of wrought-iron 
collars, which are rivetted into the pipes; the succeeding 77 feet 
6 inches are lined with copper pipes, with 23 inches bore, soldered 
into a single length, and resting in the chalk, through which the 
remainder of the hole is bored, and in which no pipes were used. 
The whole series of pipes was introduced at once, the hole having 
been prepared for receiving them as soon as it avas ascertained 
that the augers had reached the chalk stratum. The land 
springs in the gravel, above the blue clay, were kept out in the 
first instance by extra iron pipes. The spring which was found 
in the sand below the blue clay, and above the chalk, rose to 
within a few fect of the surface, but did not overflow. The whole 
of the water of this spring is, however, excluded from the well by 
the pipes with which it is lined, 
