44 
Transactions Texas Academy of Science. 
organic matter was removed, so that it would require a flow for 125 
miles to remove ninety per cent of the organic matter. 
As illustrating the vitality of disease germs, I quote the substance of 
a discussion by Mr. Gardener S. Williams published in the Transactions 
of the American Society of Civil Engineers, Vol. XLII, page 165: 
Port Pluron, at the head of the St. Clair river, sixty miles above Detroit, 
discharges her sewage into Black river. On April 16, 1892, after a 
severe winter’s freeze, dredgings were begun in this river — the excavated 
material being dumped from scows into St. Clair river. In some places 
the deposit below the mouths of the sewers amounted to over twelve feet. 
Now, the St. Clair river is eighteen miles long and after leaving the 
river the flow through St. Clair lake is very slow' indeed, so that it forms 
an ideal settling basin. The outlet of this lake is the Detroit river, 
from which Detroit takes her water supply. It is estimated that it takes 
from six to ten days for the water to flow from Port Huron to the intake 
of the Detroit water-works. From May 11th to May 28th no deaths 
from typhoid fever occurred in Detroit, and only a very few cases earlier 
in the season. On May 28th there was one death, on June 5th there 
were four, and in the next twenty-five days there were thirty-seven 
deaths from typhoid fever in Detroit out of a population of 230,000. 
Allowing ten days for the water to come from Port Huron, fourteen 
days for the incubation of the disease germs, and twenty-five days more 
from the appearance of the disease until death occurred, we have a total 
of forty-nine days as against fifty days from April 16th until June 5th 
when four deaths occurred. After dredging in Black river was stopped 
by cold weather the epidemic of typhoid in Detroit also stopped, but 
began again next spring after dredging again began in Black river. 
Just how long these germs had lain dormant in the ooze at the bottom 
of Black river is not known, but it is possible that they were there for 
years, though I have no records of the epidemics of Port Huron at hand. 
The death rate from typhoid fever is higher in the West than in the 
East, and higher still in the South. For the ten years previous to 1897 
the death rate from this cause in Pittsburgh was 81.6 for every 100,000 
population, while in Boston and New York the death rate for the same 
period from the same cause was 31.9 and 21 respectively. Examples of 
this kind might be multiplied indefinitely ; the pages of our engineering 
journals are filled with them almost weekly, and they even creep some- 
times into the columns of the daily press. 
Since the ravages of even a single form of zymotic or zymotoxic dis- 
ease may prove so deadly the necessity for the purification of drinking 
water supplies, and of the wastes that are likely to contaminate such 
supplies, is self-evident, and it remains for the engineer to accomplish 
this by constructing suitable plants for the purpose. The actual treat- 
