used by
the unwise use of such water, it will not be out of place to refer
briefly to some of the instances in which a direct connection has been
traced between a specific pollution of a certain water and disease or
death resulting from it.

Although, as has already been explained, an infected water causes
various kinds of intestinal disorders, particularly among children, the
most characteristic evidence of pollution occurs when the noxious
material comes directly from a typhoid fever patient, so that this same
disease can be recognized as transmitted to another individual or
family. This transmission of typhoid fever, while in some cases very
plainly due to other agencies than water, as, for example, milk,
oysters, and flies, yet, by far the largest proportion of the
transmitted cases comes through the agency of polluted drinking water,
and there are many examples both of contaminated wells and streams which
emphasize this possibility beyond all question.

Two historic investigations of epidemics which have thoroughly convinced
sanitarians that typhoid fever is a communicable disease and that water
is the vehicle for its transmission may be briefly cited.

In 1879 Dr. Thorne reported an epidemic in the town of Caterham,
England, which he had investigated, and disclosed the following facts:
The population of the village was 5800. The first case of fever appeared
on January 19. Others followed in rapid succession, until the number
reached 352, of whom in due time 21 died.

The possibility of infection was carefully looked into. The influence of
sewer air was ruled out because there were no sewers. The milk supply
was proved unobjectionable. No theory of personal or secondary infection
could account for the widespread prevalence, particularly as only one
isolated case had occurred during the preceding year, and this had been
imported.

Of the first 47 persons attacked, 45 lived in houses supplied with the
public water-supply, and the other two were during the day in houses
supplied with public water. Further, in the Caterham Asylum, with nearly
2000 patients, not a single case appeared, their water coming from
driven wells. Investigation of the water-supply showed the undoubted
cause of the epidemic. The public water-supply was derived from three
deep wells, connected by tunnels in the chalk. In one of these tunnels,
from January 5 to the end of the month, a laborer worked, who, though
unattended by a physician, wa