the well below.

The well was abandoned, another was bored and piped with two inch iron pipe to the depth of thirty feet. The health of the pupils has again returned to its normal standard.

Case II. In this neighborhood twelve cases of a mild type of secondary diphtheria, four cases of enteric fever, and a number of cases of gastro-enteric troubles occurred among the pupils. A well, much in the same condition as No. I was, against the advice of the health officer, "cleaned out" by simply pumping out the water and scraping the bottom. The next year the former diseases appeared but decreased in numbers and severity. The well was deepened, stone lining removed, and curbed throughout with twenty-two inch tile and cemented joints. No more trouble has occurred for two years past.

Wells supplied by water from deep strata contain few bacteria unless contaminated by surface water, in which they are usually abundant. Even then, as shown by laboratory experiments, pathogenic bacteria are unlikely to increase, but rather disappear in from two to six days, being "crowded out" by other bacteria whose natural habitat is in the same

water.

According to Bolton and Frankland this is probably true also of even the typhoid bacillus, the anthrax bacillus without spores, and the cholera spirillum.

Kraus, Wolffhugel and Reidel found similar results in hydrant water. Frankland in a series of investigations into the water-supply of London, published in 1894, shows that water, by a process of sedimentation from disuse, may become very poor in bacteria, while the muddy sediment at the bottom of wells and reservoirs still contains enormous quantities.

Rubner in an investigation of stagnant water in an unused well at Marburg, found that a specimen of the undisturbed contents showed only 1,620 bacteria per c. c., while a specimen taken after the contents had been stirred to a point of

excessive turbidity, showed 1,475,000 per c. c. and these belonged to the well itself and were not introduced by contamination from surface.

Even the deepest artesian wells contain a few bacteriafrom 4 to 33 per c. c.,-while no matter how deep an ordinary well is dug it will contain more or less bacteria, even when successfully protected from surface contamination; but it must be remembered,

Ist. That such well-water by the processes of sedimentation, before mentioned, together with some nitrification always present to some extent, becomes practically free from bacteria while the sediment at the bottom becomes far richer in bacterial constituents;

2nd. That the presence therefore of large numbers of bacteria in such a case denotes disturbance and not contamination, whilst, conversely, a small number denotes prolonged quiescence and not necessarily absence of contamination, and,

3d. That the danger in contaminated water lies not so much in the quantity as in type of microorganism and the frequency of contamination.

The experiments of Fränkel, Koch, Beumer and Maggiora show that while soil at the surface may in favorable locations teem with bacteria, there is a dividing line, varying from three-fourths of a meter in virgin soil, to about one and one-half meters in more densely populated areas, below which very few bacteria are found, and that as a consequence the "ground water" region is nearly unpolluted.

Typhoid bacillus has been found to grow through the year at a depth of three meters and the anthrax at one and onehalf meters, but no pathogenic bacteria have been found in the deeper layers of the earth. (Fränkel.)

It is also shown that the numbers of bacteria are greatly increased,

Ist. By cultivation and strength and character of fertili

zers;

2nd. By the density and permeability of the soil; and, 3d. By the density of the population.

The rural population derives its water almost exclusively from shallow wells-(those less than fifty feet in depth and sunk in superficial layers of soil overlying impermeable strata of clay or dense rock)—and at the same time it is the almost invariable rule to dispose of the sewage of the premises in such close proximity to, and in such a manner, that the water is in a state of constant contamination and grossest pollution, although at the same time clear, sparkling and palatable. For the organic filth from cesspools, drains, etc., in its passage through even a few feet of soil is deprived of suspended matters, but not of its dangerous properties, while the well has become only a gigantic culture-tube for the propagation of all forms of bacteria, -pathogenic and non-pathogenic. Shallow wells are never above suspicion as to the purity of their waters.

The distance within which a well draws water to itself when its own water level has been depressed by pumping, depends on the amount of depression and nature of the soil, and has approximately a radius of 15 to 39 times its depression if in fine sand or gravel offering considerable resistance; 57 times the depression if in chalk with fissures; 68 to 100 times the depression if in coarse gravel allowing free passage; and 143 times the depression in red sandstone with fissures.

Fränkel has shown that the filtration at low pressure, of water through fine sand one meter in thickness removes almost all pathogenic bacteria.

All wells that are "dug," must be so situated that the underground waterflow shall be toward the possible sources of pollution and at a distance of 100 to 160 times any depression of its water that may likely occur by pumping. The sides should be lined down to the surface of the underflow with stone or brick carefully laid in hydraulic cement; or Portland cement tiles of desirable dimensions should be used

The

and the joints carefully sealed with hydraulic cement. mouth of the well should be closed over with large flat stones laid in cement, or some other expedient used to effectually exclude any foreign substances, and should be at least two feet above the surface of the ground, and protected with a coping.

The water should be raised by a metal pump supplied with a contrivance to produce a suitable degree of aeration of the water within the well. The waste water from pumping should be carefully conducted away to a safe distance, and the pump should not reach nearer than 18 inches of the bottom of the well, thereby leaving the sedimentary deposit undisturbed.

WATER-BORNE DISEASES-DUE TO CARELESS DISPOSAL OF SEWAGE.

BY J. NOER, M. D., OF STOUGHTON.

Asiatic cholera, typhoid fever, dysentery and acute diarrheal diseases are typical water-borne maladies, having their origin in sewer-polluted water or food-supply. Most of these diseases have as their causative agent a specific contagious germ which finds a congenial habitat in putrescible matter such as sewage. It is believed that some of the putrefactive bacteria may cause simple diarrhea by their irritative action on the intestinal mucous membrane or by the production of ptomaines which may be absorbed or act as local irritants.

Sewage containing the infective germs or bacteria may pollute the water-supply and start an epidemic in a variety of

ways.

It is universally admitted that cholera, typhoid fever and dysentery never occur except through the action of a specific bacterium, which has a different biologic and morphologic characteristic in each disease. These bacteria are not, or at least are very rarely, transmitted by the air or clothing, but almost invariably directly or indirectly through the water-supply.

How do these tiny vegetable organisms get into our drinking water and from thence into milk or other food of which we partake and thus become victims to the disease?

River- and lake-water polluted by sewage from our cities with water-carrying sewer systems, or which are polluted by overhanging privies or by cesspools near their shores, is one of the most prolific sources of water-borne diseases.

Well-water from the ordinary domestic well, where the top and the curbing are imperfectly protected from the surface