This contingency is fully provided for in the Albany plant. The orifices are of such size that even with a filter just scraped and put in service, with the minimum loss of head, with the outlet-gate wide open, and with the water-level in the pure-water reservoir clear down—that is, with the most unfavorable conditions which could possibly exist—the rate of filtration cannot exceed 5,000,000 or 6,000,000 gallons per acre daily, or double the nominal rate. This rate, while much too high for a filter which has just been cleaned, is not nearly as high as was possible, and in fact actually occurred in the old Stralau filters at Berlin, and in many English works; and, further, such a condition could only occur through the gross negligence of the attendants, because the rate of filtration is indicated clearly at all times by the gauges. These regulating-devices have been specially designed to show the rate with unmistakable clearness, so that no attendant, however stupid, can make an error by an incorrect computation from the gauge heights. It is believed that the advantage of clearness by this procedure is much more important than any increased accuracy which might be secured by refinements in the method of computation, which should take into account variations in the value of the coefficient of discharge, but which would render direct readings impossible. In designing the Albany plant the object has been to combine the best features of German regulation with the economical and convenient features of the older English system, and filters are allowed to respond to the pumps within certain limits, while guarding against the dangers ordinarily incident thereto. RESULTS OF OPERATION. The filters were designed to remove from the water the bacteria which cause disease. They have already reached a bacterial efficiency of over 99 per cent, and it is expected that their use will result in a great reduction in the death-rate from water-borne diseases in the city. They also remove a part of the color and all of the suspended matters and turbidity, so that the water is satisfactory in its physical properties. The filters have reached with perfect ease their rated capacity, and on several occasions have been operated to deliver one third more than this amount; that is to say, at a rate of 4,000,000 gallons per acre, daily. COST OF CONSTRUCTION. The approximate cost of the filtration-plant complete was as follows: Land $8,290 Pumping-station and intake 49,745 Filters and sedimentation-basin, with piping 323,960 Pure-water conduit and connection with Quackenbush Street pumping-station 86,638 Engineering and minor expenses 28,000 ———————— Total $496,633