“Far from it! There’s harm enough in sewer-gas, but no germs. The harm is that the gas reduces vitality, and makes one more liable to disease attack. It’s just as true of coal-gas as of sewer-gas, and more true of ordinary illuminating gas than either. I’d much rather have bad plumbing in the house than even a small leak in a gas-pipe. No, Mrs. Sharpless, if you waited all day at the mouth of a sewer, you’d never catch a germ from the gas. Moreover, typhoid doesn’t develop under ten days, so your odorous outbreak of the day before could have had nothing to do with Mr. Clyde’s illness.” “Perhaps you’ll give us _your_ theory,” said the old lady, with an elaboration of politeness which plainly meant, “And whatever it is, I don’t propose to believe it.” “Not mine, but the City Water Commissioner’s. Mr. Clyde’s case was one of about eighty, all within a few weeks of each other. They were all due to the criminal negligence of a city official who permitted the river supply, which isn’t fit to drink and is used only for fire pressure, to flood into the mains carrying the drinking supply.” “Then why didn’t the whole city get typhoid?” asked Mr. Clyde. “Because only a part of the system was flooded by the river water. The problem of the city’s experts was to find out what part was being contaminated with this dilute sewage. When the typhoid began to appear, the Health Department, knowing the Cypress supply to be pure, suspected milk. Not until a score of cases, showing a distribution distinct from any milk supply, had appeared, was suspicion directed to the water supply. Then the officials of the Water Department and Health Department tried a very simple but highly ingenious test. They dumped a lot of salt into the intake of the river supply, and tested hydrant after hydrant of the reservoir supply, until they had a complete outline of the mixed waters. From that it was easy to ascertain the point of mixture, and stop it.” “Our river water is always bad, isn’t it?” said Mr. Clyde. “Last summer I had to keep Charley away from swimming-school because the tank is filled from the river, and two children got typhoid from swallowing some of it.” “All foolishness, I say,” announced the grandmother. “Better let ‘em learn to swim.” “Can’t you swim at all?” asked Dr. Strong, turning to the seven-year-old. “I went five strokes once,” said Charley. “Hum-m-m! Any other swimming-school near by?” “No.” “And are the children about water at all?” Dr. Strong asked the mother. “Well; there are the canal and the river both near us, you know.”