430 Reviews—Beeby Thompson’s M. Lias, Northampton. 
Owing to the increased amount of water needed for the town of 
Northampton, and partly owing to improved systems of agricultural 
drainage, the water derived from the deep wells in the Middle Lias 
was found to be insufficient, Still deeper wells were made in the 
hopes of reaching water- -bearing: Triassic rocks; but these were 
failures. 
Mr. Thompson has for some years past advocated that a system of 
dumb-wells be constructed—about 100 feet in depth on the average. 
“These dumb-wells would all be situated in the valleys, and would 
generally require to be cut through a little alluvium and river 
gravel, and through the Upper and Middle Lias. The wells might 
be lined with brick, and then filled up with coarse gravel, broken 
brick, or any good porous material to within 36 ft. or 40 ft. of the 
top, the material to get finer towards the top, in imitation of the 
filter beds of the London water companies. The depth of 38 ft. 
to 40 ft. not filled with gravel is given to enable the water running 
in from the river gravel, as well as that from the surface, where 
such water is desirable, to have a good fall, whereby it may be 
effectually aerated before entering the chief filter bed.” 
The author would take advantage of the river gravel as a primary 
reservoir and filter-bed, whence the water would be conveyed into 
the Marlstone. He mentions that at the present time water obtained 
from the river gravel is clear, and free from suspended impurities, 
and would still be so if his plan were adopted, so that, in his 
opinion, there would be little or no silting up of the dumb-wells. 
Additional supplies of water might also be obtained from the river 
by means of pipes when the water was sufficiently high for it to be 
well spared, and this would tend to prevent the injuries that arise to 
the banks from overflowing. The author, therefore, contends that 
his scheme, of which he gives full details, would improve a large 
district now injured by floods; it would furnish an abundant water 
supply in a natural reservoir (the Middle Lias); and the water 
would be very pure, because it would be filtered before entering the 
well, and filtered again in the well before entering the most effectual 
filter the Marlstone itself, while it would be well aerated by its fall. 
Various objections have been raised against this scheme, and these 
are fully discussed by Mr. Thompson. Perhaps the most serious 
objection is that a scheme of this nature has not been tried before in 
this country, and that it must necessarily be an experiment. Such 
an objection might have been urged against some of our deep 
borings! Another question is whether the water would go away 
through the dumb-wells. Water obtained from old wells was of an 
artesian nature rising formerly at one place 90 feet above the water- 
bearing rock. This, however, was before the water-level had been 
reduced by the large supplies procured, and so long as large supplies 
are pumped up, there would be no danger of overflow from the 
dumb-wells. The dip of the beds is considered too slight to offer 
any obstacles to the scheme. The Upper Lias is 170 to 190 feet 
thick, and the author calculates that there could be a head of water 
of 110 feet at Northampton, before the dumb-wells would cease to 
act or occasion loss. 
