The first sample of water was taken from a well where fourteen persons were simultaneously attacked in December last by typho-malarial and diarrhœal diseases. All had been drinking water from this well, and had it not been for the timely help of the physician who condemned the water. SERIOUS RESULTS WOULD HAVE FOLLOWED. On examination the cess-pool was found to be connected directly with the well by a pipe, and when the cess-pool became full, its contents regurgitated into the well. The Board of Health examined the premises, condemned the well and ordered that both privy vault and cess-pool be cleaned out without delay. I understand that it is quite common in this city to connect the cess-pool with the well by a pipe so that the waste water may be readily conveyed away; but if people knew the danger to be feared from such an arrangement, greater care in the construction of drains would be exercised. Hundreds of cases might be related where in houses fitted with all that taste could desire, and gold procure, a siphoned trap, or in the absence of a trap, an imperfect joint, or an old brick drain, or riddled soil pipe, defects easily remedied if known to exist, have undermined the health of adults and slain the little ones. In the first sample a large quantity of animalculæ were revealed by the microscope. Fox states that “the existence of animal life in a water affords good evidence in itself of the presence of a very sensible amount of organic matter, _alias_ filth. These little creatures feed and flourish on what we call organic matter, and in perfectly pure water they cannot live. A perfectly pure water contains no suspended matter nor any animal or vegetable life. The ova of the round and the thread worms, the eggs and joints of the tapeworm and small leeches, which may give rise to grave disorders, should not be forgotten in making microscopic examinations of drinking waters.” Good water is both a necessity and a priceless blessing. Foul water is a scourge and a messenger of death. No one except a brute would hesitate which to choose if he could tell one from the other. It is only with the grosser pollution of water that chemists can apply their science. Infinitesimal pollution cannot be estimated by the skill of any chemist. It is the careful physician who decides more accurately in regard to the purity of water than the chemist. Sir Benj. Brodie in speaking of the detection of infinitesimal pollution says: “I think you have a much better chance of getting at these relations through accurate medical statistics, properly applied, than you have through chemical analysis, because chemical analysis is one of the poorest things possible to reach those delicate quantities. You cannot get at these small quantities at all; chemical analysis must be limited by our power of weighing and measuring. It may go on to a certain point, but we cannot go beyond that point.”