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March, 1917 boats operating during the past season were equipped with apparatus’ for sterilizing their drinking water by ultraviolet rays. Eleven of these ves- sels used a “pressure-type” apparatus and two a “gravity-type’. The pres- sure type of apparatus consists of a cast iron cylindrical shell, with a quartz tube through its axis and containing baffle plates so arranged as to spread the water in a thin film while passing through the ultraviolet field. The ultraviolet lamp in use during the summer of 1915 was a quartz lamp of the “pistol” type, which was inserted on the inside of the quartz tube. In. the gravity type of apparatus the lamp is suspended above a baffled treat- ment chamber, where the water is exposed in a thin film twice during its passage by the lamp. The gravity apparatus had only a capacity of about 100 gallons an hour, which is consid- erably below the maximum amount needed on most lake vessels, and as a result it was used solely for filling water bottles, pitchers, etc. ‘The pres- sure apparatus, on the. other hand, was rated either at 200 or 1,000 gal- lons an hour, and the water was treated while under pressure on its way to the distribution system. The ultraviolet type of sterilizing apparatus early attracted our atten- tion. The results of laboratory examinations demonstrated that the apparatus in the form described was inefficient. The company manufactur- ing the apparatus at once set to work to remedy the obvious defects. They have equipped a new type of lamp with an automatic device for relight- ing whenever it goes out because of breaks in the current. It is claimed that this new lamp emits a_ higher per cent of ultraviolet rays, and that it will stand a much greater fluctua- tion in voltage than the old _ type without going out. The company has also developed an arrangement where- by the water will be shut off auto- matically when the lamp is out and calcium hypochlorite, a small dose of a solution of this chemical being added to the storage tank each time it was filled. Calcium hypochlorite, a very efficient sterilizing agent when properly administered, is not to be recommended on vessels for the rea- Nore—/yose Lite SOmertses THE MARINE REVIEW eee 3S. To operate this apparatus, water was pumped from the sea _ cock by means of an ordinary steam-boiler injector, and when discharged from the injector it was raised to a tem- perature of about 160 degrees Fahr. After leaving the injector, a steam Drinking USCA TOS MIG TUM MWISTOLS pn far SVSTCM?7 of Ths Coruiecrior7 FIG. 4—-TANK FILLED FROM SEACOCK BY GENERAL SERVICE PUMP. DRINK- ING WATER DISTRIBUTED BY GRAVITY son that it depends for its constant efficiency upon some person to cor- rectly proportion the dosage added to the tanks each time they are filled. On one of the vessels” using this chemical the water, at the time of inspection, had an extremely strong chlorinous taste. This indicated an overdose, and was evidence that there was no close control of the amount added. This method is further open to the criticism that its uniform eff- ciency rests entirely upon human agency, which can never be wholly dependable. Sterilization by Heat from Steam Jet. —There were five vessels which treat- FIG. 3—TANK FILLED FROM SEACOCK BY GENERAL SERVICE PUMP. DRINKING WATER DISTRIBUTED BY SPECIAL PUMP remain so until it is relighted and yegains its point of maximum effi- ciency, when the water is again start- ed automatically. Chlorine Disinfection—The water sup- ply of five vessels was treated with ed the drinking water by heating with a steam jet. This scheme was de- vised by the Detroit city board of health in connection with the study, ‘conducted by the board, of drinking water used on vessels entering Detroit. ~tank. jet was added to the line, further in- creasing the temperature to about 230 degrees Fahr. In this discharge line was placed a thermometer, and upon starting, the water was allowed to run to waste until the last-mentioned tem- perature was reached, at which time the waste line was closed and the water passed through several hundred feet of pipe placed inside a cylindrical tank through which cold water was circulated. This cooling tank reduced the temperature to about 130 degrees Fahr. From the cooling tank the water was run into the drinking-water storage tanks. This apparatus, while able to pro- duce good results under careful man- agement, was liable to be mishandled. In the first place, it depended en- tirely upon the observation of the engineer as to the reading of the thermometer in order to be certain that no water reached the storage ‘tanks which had not been heated to the above-named temperature, and as the water after heating was passed immediately to the cooling tank, it was not held at the high temperature © except for comparatively a few sec- onds. With a few modifications, the appa- ratus could be made “fool-proof” and automatic in its operation. These im- provements consist in adding a sup- plementary tank, in’ which the hot water could be stored for perhaps five minutes before entering the cooling It. would also be possible to install a thermostat just beyond this retention tank, which would auto- matically control a waste valve and a valve leading into the cooling tank, so that unless the water leaving the retention tank was up to the required