Page:Popular Science Monthly Volume 14.djvu/537

Rh stoned up, belonging to Otto Schmidt. All of these houses were invaded by the fever. But it is necessary to account for the contamination of the water. Here comes in the fact that gave me the key to the mystery. On the 20th of September, as I have already stated, there occurred a severe thunderstorm. It was so violent that a large amount of the rainfall was carried off as surface-wash. It did considerable damage to the gardens, and, among other things, filled up to overflowing the vault attached to Otto Schmidt's house. Here was deposited all the excrementitious matter from this severe case of the disease. It was easy to observe, from the appearance of a board walk, of the grass and ground, that the overflow had scattered material of this kind in the neighborhood of the well. Whether it ran into the well, or filtered through the ground, it is difficult to say; either could have occurred, or possibly both.

Now observe what occurred. Fourteen days after the shower, the 4th of October, a case of the disease broke out in the house g. Twenty days after, the first case was taken down in the house c; thirty and thirty-six days later, two cases in d, and two cases at intervals of six and twelve days later in the house h. These were the families habitually dependent on the Schmidt well for their supply of water.

Admitting that I am right in tracing these cases to the contamination of the well t, by the shower of the 20th of September, we have left two families in which occurred five cases of the fever who did not make use of this well. On questioning the people in the houses e and, f, I learned that they crossed the road and drew water from the well s. This missing link in my chain of cause and effect made a halt in my investigations. I had fancied that I was so near success that I took this disappointment as a sort of personal matter, and was half inclined to give the whole thing up. I made another effort; I crossed the road and investigated the well and its owner. There was no fault to be found with the well, which was a "drive well"; but the owner told me that it occasionally became dry, and was in that condition before and for a week or two after the great shower of September. Back I went to my fever-houses, and exploded this question like a bomb-shell in the midst of their inhabitants: "Where did you go for water when the Bogert well was dry?" "Oh, we went to Mr. Schmidt's well."

After this testimony let us trace the course of the invasion a step further. The fever appeared among the inmates of the house f on the 20th of October, and of the house e on the 28th. Had we no further evidence, here is sufficient to render probable that these cases were due to drinking the infected water from the Schmidt well. But we may strengthen it by negative evidence. The inhabitants of the uninfected group of houses on the opposite side of the street at M never used the suspected well. When the well s became dry they resorted to the well at x. There is one other group of uninfected houses, two of them belonging to the same block as the infected houses, and one situated on