"Certain trades pour their refuse water into rivers, gas-works;
slaughter-houses; tripe-houses; size, horn, and isinglass manufactories;
wash-houses, starch-works, and calico-printers, and many others. In houses
it is astonishing how many instances occur of the water of butts,
cisterns, and tanks, getting contaminated by leaking of pipes and other
causes, such as the passage of sewer-gas through overflow-pipes, &c.

"As there is now no doubt that typhoid-fever, cholera, and dysentery may
be caused by water rendered impure by the evacuations passed in those
diseases, and as simple diarrhoea seems also to be largely caused by
animal organic [matter in] suspension or solution, it is evident how
necessary it is to be quick-sighted in regard to the possible impurity of
water from incidental causes of this kind. Therefore all tanks and
cisterns should be inspected regularly, and any accidental source of
impurity must be looked out for. Wells should be covered; a good coping
put round to prevent substances being washed down; the distances from
cess-pools and dung-heaps should be carefully noted; no sewer should be
allowed to pass near a well. The same precautions should be taken with
springs. In the case of rivers, we must consider if contamination can
result from the discharge of fecal matters, trade refuse, &c."

Now, suppose all such precautions have been disregarded. Suppose, as is
most usual, that the well is dug near the kitchen-door,--probably between
kitchen and barn; the drain, if there is a drain from the kitchen, pouring
out the dirty water of wash-day and all other days, which sinks through
the ground, and acts as feeder to the waiting well. Suppose the
manure-pile in the barnyard also sends down its supply, and the privies
contribute theirs. The water may be unchanged in color or odor: yet none
the less you are drinking a foul and horrible poison; slow in action, it