34 
POPULAR SCIENCE REVIEW. 
These high peat bogs are reservoirs of water, which they 
collect in winter and yield gradually in summer. They gene- 
rally lie at too high a level to be cultivated for grass or corn, 
but they are capable of some improvement as rough upland 
pasture. This improvement is often secured by deeply trenching 
the bogs in various directions ; the water then drains off, the 
soil becomes drier and affords feed for sheep. This process is 
largely going on, and if continued will, in the course of only a 
few years, make its results seriously felt on the summer and 
autumn flow of the rivers in the north-east of England. Such 
results will be less felt, indeed may be comparatively unimpor- 
tant, in most rivers on the western side of the great central 
watershed of England ; for there the rainfall is much greater, and 
the periods of drought are shorter. But on the eastern side of 
the watershed it is simply equivalent to destroying a large 
number of natural 44 compensation reservoirs,” which at present 
serve to diminish the winter floods and to augment the summer 
flow. The additional value conferred on the uninhabited upland 
moors is but small ; the loss to the populous cultivated low- 
lands is immense. 
The late floods have once more made evident the importance 
of storing the surplus rainfall for summer use. This, with 
more embankments and fewer weirs, will lessen the floods. 
Some day probably all this will be done, but at enormous 
expense. Meanwhile it might be well to see to the preservation 
of those reservoirs which Nature has herself provided. 
A supply of water and the disposal of sewage are two of the 
most difficult problems of modern times ; whilst either, taken 
alone, would in many cases be comparatively easy. The readiest 
mode of getting rid of sewage is to pour it into the rivers and 
streams ; but this fouls the natural source of water supply. 
Pollution of rivers by such means will in time be largely 
checked ; we shall some day discover that sewage is too valuable 
to be thrown away. But even if the utilisation of sewage should 
not prove actually profitable, it will be found advantageous to 
spend public money on this, and thus to prevent the fouling of 
rivers to the extent now practised and each year increasing. 
By these and other means the pollution of rivers may be greatly 
reduced, but it can never be wholly prevented ; and it is useless 
to look for a supply of water for drinking purposes from rivers 
which traverse manufacturing or populous districts. 
44 Doctors disagree ” in many things of great moment to the 
public health, but in none is this disagreement more to be 
regretted than in questions relating to water supply. Complete 
accord as to opinions and inferences is not to be expected, but 
we may certainly hope for more agreement as to facts and as to 
the mode in which these facts are published. Carefully prepared 
