THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
39 
The water would be well aerated by the fall into the dumb-wells. 
This aeration is a very important matter in the purification 
of water, and yet it seems to be rather neglected in most 
arrangements for the artificial purification of water. The 
best proof of the value of aeration is found in the fact that the 
free oxygen in water is always in the inverse ratio of the 
organic contamination. 
Water collected and stored as suggested would be perfectly 
safe until wanted, it would be of an equable temperature all 
the year round, cool and ref reshiny in summer, and not liable to 
freeze in winter, in these respects being far superior to water 
stored in open reservoirs. A large open reservoir must 
during the summer months breed large numbers of infusorial 
animals, and although these may be removed by the filter 
beds, the water is liable, on account of its temperature, to 
again breed such afterwards. 
One other advantage of the underground reservoirs might 
be here pointed out —the filter beds cannot be overtaxed so as 
to supply imperfectly filtered water. Of the water which is 
put in, it maybe months or even years before that same water 
is utilised in the town, and in all cases it would amount to a 
considerable interval of time, because it could only reach the 
pumping station by pushing other water before it through the 
filtering medium, and being itself pushed. 
The following remarks, quoted from Mr. 0. E. de Ranee's 
work “ The Water Supply of England and Wales,” are 
very pertinent to the question here dealt with. 
“In regard to their general fitness for drinking and 
cooking, the Rivers Pollution Commissioners classify waters 
in the order of their excellence, in respect to wholesomeness 
and palatability as follows :— 
Wholesome 
Suspicious 
Dangerous 
l 1. Spring water 
<j 2. Deep well water 
( 3. Upland surface water 
f 4. Stored rain water 
< 5. Surface water from culti- 
( vated land 
f 6. River water which sewage 
<[ gets access to 
I 7. Shallow well water 
f 
i 
Very 
palatable. 
Moderately 
palatable. 
Palatable. 
The value of spring and deep well water is not merely due to 
their great intrinsic chemical purity and palatability, but to 
their being peculiarly suited for domestic supply, from their 
almost invariable clearness, transparency and brilliancy, and 
their uniformity of temperature throughout the year, rendering 
