--------------------------+-------------------+--------------------- | RATE PER 100,000 | PERCENTAGE Cause. +---------+---------+-----------+--------- | 1908-12 | 1913-17 | Reduction | Increase --------------------------+---------+---------+-----------+--------- Total[A] | 14.90 | 14.78 | 1.2 | ... Typhoid, total | 34[B] | 17 | 50.0 | ... Typhoid, city | 26[B] | 8 | 69.2 | ... Pneumonia | 100 | 107 | ... | 7.0 Tuberculosis | 133 | 138 | ... | 3.7 Diarrh[oe]a and Enteritis | 139 | 128 | 7.9 | ... under 2 years | | | | --------------------------+---------+---------+-----------+--------- [A] Rate per 1,000. [B] 1906-10, epidemic years 1911-12 excluded. One further objection might be made: that the raw water was not infected during 1913-17 or infected to a smaller extent than during the previous period. Attempts to isolate _B. typhosus_ from the raw water have invariably been futile but their presence in 1914 might be inferred from the fact that during the latter part of the summer of that year an epidemic of typhoid fever occurred at Aylmer, a village that discharges its sewage into the Ottawa River about six miles above the Ottawa intake. Hull, situated on the opposite bank of the river and having a population of 20,000, takes its water supply from the same channel that supplies Ottawa but at a point a few hundred feet further down stream. During November and December, 1914, some 200 cases of typhoid fever (incidence 1,000 per 100,000) occurred in Hull as compared with 28 in Ottawa. As the Ottawa intake is situated between the Hull intake and the outlet of the Aylmer sewer it is incredible that the Ottawa raw water was not also infected. In 1916 a liquid chlorine plant was installed in Hull, but in 1917, owing to an accident, it was out of commission for a short period and at least 100 cases of fever developed during the following month. During the same period only two cases were reported in Ottawa and of these one was obviously contracted outside the city. In view of the preceding facts it must be granted that the improvement in the typhoid rate of Ottawa can be definitely attributed to an improvement in the water supply caused by chlorination.