*of population, there are many parts of Mauritius which have 
■quite but all rural character. 
The inhabitants and establishments are so closely concen- 
trated in some of these places, that in dealing with them, in 
all that relates to drainage and water supply, they must be 
treated as parts of a town. 
Formerly, when the population was more thinly scattered, 
little harm was done to the purity of the water of the streams 
the drainage and impure matters belonging to a few people 
being easily disposed of, without polluting the streams ; at 
present the case is far different, and in places where men and 
animals, and manufactories are in such large numbers, the 
impurities which result cannot be got rid of so easily ; it is 
altogether useless to enact that manufactories and objection- 
able establishments shall be placed at not less than a given 
distance from streams. Whenever there is a great and conti- 
nuous deposition of impurities, such impurities will necessarily 
find their way to the water courses, unless carried off to the 
sea by an artificial system of drainage. 
The water courses are the natural lines of drainage of the 
country, and are necessarily the lines of lowest level available. 
If the surface from which the drainage is collected be unoc- 
cupied and clean, the stream will of course be pure, but if the 
water course runs through a densely peopled district, it is 
impossible, but that the surface drainage will pollute the 
stream. 
Again, people must wash themselves and their clothes. 
How is this to be done, in a crowded district without pollu- 
tion to the stream ? 
In order to overcome this difficulty, it has been proposed 
by some that small basins should be constructed at chosen 
spots near the rivers, in whieh basins people might wash, 
without defiling the streams, but it does not seem to have 
been considered, what is to become of the dirty water of the 
basin. It cannot be got rid of, except by allowing it to flow 
back into the river lower down. 
There are many other ways in which the water of small 
streams which traverse populous districts must necessarily be 
rendered impure and unfit for drinking; and this more es- 
