however, that this reservoir could have very little, if anything, to do with it It was learned, however, that water was so distributed in Manhattan Island as to make the liability of infection greater in the upper than in the lower portion of Manhattan, if water were in any wise responsible. When the water reaches the city from the aqueduct, some of it enters the Jerome Reservoir as previously pointed out, while the Manhattan supply crosses the Harlem River at High Bridge, going into Manhattan at 172nd Street. A portion of the water is pumped directly from the aqueduct to a water tower which supplies all norther New York City. The aqueduct then continues its course to the 135th Street gates, from which point mains run to the reservoirs in Central Park. Meanwhile supply pipes from the aqueduct and mains go to pumping stations which distribute a portion of the water to the middle section of Manhattan, the remainder of this middle section receiving its supply from water which has been stored for a time in, the Central Park reservoirs. Thus there are portions of fresh, and portions of stored water, supplied to the middle section of Manhattan. The lower section of the city receives water only from the reservoirs in the park.

When this information was received from the Engineer's office of the Department of Water Supply, Gas and Electricity, the scheme of distribution seemed to fit in with the number of cases in each of these three parts of Manhattan Island, so that on considering about 800,000 people each in upper, middle and lower Manhattan, it was found that to every six cases among the upper third, there were only four in the middle third and but three in the lower third. Where the fresher, less sedimented water was used, the most cases developed. Where a mixture of sedimented and fresh water was used fewer cases developed. and, where only a sedimented water supply was consumed, the least number of cases developed.

There was some relation between the number of infections developing in a given period, the amount of free chlorine available (as the result of chemical treatment of the water), and the number of bacteria in the water for the corresponding period. This is shown in the following chart exhibiting data obtained from the Water Department.

Key. The typhoid fever, coli, and total bacteria curves, are leveled to a certain extent within 10-day periods in order to present their general characteristics more clearly to the eye.

The "total bacteria" represents growths in 48 hours at 20° c., those at 371⁄2° c. not being available.

They ran as high as 7,500 one day. On 13 days they exceeded 1,000, on 7 days they exceeded 2,000. On 4 days they exceeded 3,000. The coli were found in 1 c. c. on 13 days, in 10 c. c. on 48 days.

The chlorine curve represent daily quantities and, at the highest point, is 9.5 parts of free chlorine per million parts of water.

No typhoid bacilli were found in the water but inference was strong enough to stimulate a regular and daily use of a larger amount of the germi

cidal material. The chlorine has been maintained at 0.35 parts or more of free chlorine per million parts of water, ever since, and a beneficial result seems to have followed.

A study was made of the reported cases for the first six weeks of the year 1912, and the figures disclosed compared with those of the four preceding years, on the one hand, and the same periods of 1913 and 1914, on the other. The average number of cases for the four years, 1909-1912, was 125, whereas the average for the succeeding two years was but 66. Presuming that the inference is correct, it must not be supposed that these figures could apply to the entire year. Contrary to general belief, the typhoid bacillus preserves its vitality longer in a water, at or near 40 degrees centigrade temperature, than in 60 degrees or higher, the cold not being sufficient to destroy the germs, though it seems to shrivel them, as it were, and increase the consistency of the protoplasm, thus bringing the bacilli's powers of resistance nearer to that of spores.

Fly Transmission.-Flies no doubt carry typhoid bacilli, just as they carry other micro-organisms. Platings on which these insects have walked have shown the extent to which a fly's feet and legs may be contaminated, but no localized outbreak has ever been traced in New York City to such a cause. Some observers attribute two outbreaks, one in Brooklyn and on in Queens Borough, occurring at the same time, to this method, the investigators of the Health Department, however, found an identical raw milk supply in each borough, with ninety per cent. of the patients using this milk, whereas the proportion of persons supplied in the community at large was but forty per cent. The company operated

a number of creameries and only those customers receiving the milk furnished by a certain creamery came down with the disease. The fallacy of a special fly season prevalence is shown in the chart below. The onsets represented for each of the Boroughs in the down lines are set back to correspond with the time of infection. The topmost line represents the temperature, and shows that the most favorable period for fly development occurred ten days prior to the date when infections took place.

Prevalence In Other Cities Compared.

The methods of investigation of typhoid fever cases and analysis of reports and histories, used in New York City, have been considered in general, though necessarily in a superficial way. It will be interesting to compare the death rate of New York City with that of other cities in the United States, and cities in Europe. As compared with the former, New York City stands very well indeed. The European cities, for the most part, have lower death rates, though the reduction of the rate in this city during the last few years has progressed at a rate equal to that of any other city in the world. The following table shows the number of deaths from typhoid fever per 100,000 of the population for the cities in the United States having 500,000 inhabitants or more.

Pittsburgh

557,772 89.95

29.96

Baltimore

574,577 33.32 42.07 27.32

Detroit

25.75 12.71 19.34 23.88 31.48 22.4 590,000 23.49 19.19 15.95 18.04 24.23 21.65 13.

It will be seen that New York stands first, Boston and Chicago second and third. There are several of the smaller cities that have a slightly lower death rate, among which may be mentioned:

59.72 13.8

23.50

These are also based on the 1913 figures.

Turning to the comparisons with European cities, the following table shows the death rate for recent and former years, and the comparative progress made by each city.

Typhoid Fever In New York City Compared With Certain Cities In Europe. Deaths per 100,000 population.

The following table shows the cases, deaths and death rates in New York

City for a number of years: