220 Influence of the Physical Character 
rainy days when very little rain falls. For one, two, or 
three days, we have heavy showers, when all the water- 
courses are flooded. In connexion with the afore-mentioned 
geological formations this is an important fact. If we have 
20 or 30 showery days, and only -100 of an inch of rain falls 
in each day, we may rest assured that a meagre portion of 
this will ever reach the rivers. The soil absorbs it rapidly, 
and it is as rapidly evaporated, though not appreciable to the 
eye. Then, if we have four or five days of heavy rain, with 
an average of three inches per diem, this will quickly flow to 
the river basins, and produce floods. We are led into error and 
confusion if we estimate the fall of rain, in a district, at so 
many feet per annum, without any reference to geology, 
or to peculiarities of climate. We ought rather to estimate 
the fall of rain on those days when it 1s sufficient to flood the 
creeks. If the annual fall of rain in Victoria were concen- 
trated in five or six days, I can easily believe that it would 
nearly all reach the rivers; but, fortunately, our climate is 
differently arranged. 
In a country like this it is not unprofitable to consider 
every fact, which bears even remotely on the permanence 
of the supply, or the purity of the water. 
In constructing reservoirs in the inland districts, for sup- 
plying a town where the population is not considerable, in 
situations where no permanent stream is sufficiently near, it 
will be necessary to resort to filtration on a large scale. This 
will remove the grosser impurities, but it cannot be denied 
that this fails to remove animalcule and chemical impurities. 
When supplied to persons who are able to resort to those 
appliances for purification, taught by the chemist, it becomes 
comparatively pure, but to the mass of the population it is 
positively injurious. Whatever can be done to remedy such 
an evil ought to be done, at any pecuniary sacrifice, for the 
results consequent on ‘its removal cannot be overstated in 
their importance. It would be quite possible to extend these 
remarks, to apply them in detail to the rivers in our imme- 
diate neighbourhood, but this, I fear, would be merely useless. 
I have endeavoured, with how many short-comings I am only 
too conscious, to indicate to what extent we are indebted to 
scientific observations, and to principles founded on the 
unerring precepts of sciences in all inquiries of this kind, 
and to show how utterly indefensible it would be to rely 
upon either what is commonly called “experience,” or 
“ practical knowledge.” 
Science, our helper in the humblest as in the greatest 
