THE PUBLIC AQUAEIUM 279 



wooden tank 11 feet in diameter by 6 feet deep. It is supplied with 

 steam from the heating plant at about 5 pounds' average pressure. 

 Having given satisfactory service for several years, this form of 

 water heater is recommended as effecti^'e and durable. 



The sea water supplied to the entire series of tanks containing 

 tropical fishes is easil}^ kept at a temperature of about 72° F. 



HEATER FOR FLOOR POOLS 



Some of the lung-breathing marine animals, such as sea turtles, 

 sea lions. West Indian seals, manatees, porpoises, and sea birds that 

 go south in winter, can not thrive in water of low winter temperature. 

 For most of these the temperature should be ke^)t at 60° or 65° F. 

 Sea turtles do not feed at all when kept in chilly water. 



The heater used in the New York Aquarium for warming water 

 pumped from the harbor is a spiral iron coil covered with i^-inch 

 sheet lead closely fitted to the coil. The iy2-inch pipe has a 3^-inch 

 outlet. The harbor water is of low salinity, but the animals kept 

 in it, being lung-breathers, do not actually require water of ocean 

 salinity, although they might be benefited by it. Some of them are 

 heavy feeders, and the water soon becomes foul and must be drawn 

 off every evening. Seals and sea birds can be kept for months in 

 fresh water but eventually suffer for lack of sea water. Sea birds 

 must sooner or later have sea water to drink. The water pumped 

 from the harbor, being more or less fouled with sewage, is filtered 

 as well as warmed before being supplied to the floor pools. 



HEATER FOR FRESH WATER 



The Avater supply for pools containing pond turtles and alligators 

 requires, warming in winter before such animals will feed freely. 

 For this purpose a galvanized-iron cylinder provided with a spiral 

 copper steam coil is used. The coil is of fi/^-inch size with i/4-inch 

 outlet. The winter temperature of water for alligators and croco- 

 diles is maintained at about 85° F. ; that for fresh-water turtles is 

 10° lower. 



REFRIGERATING PLANT 



In providing equipment for cooling fresh water, the aquarium 

 builder has numerous types of refrigerators from which to clioose. 

 The New York Aquarium has a two-cylinder, 7 by 7 inch, electri- 

 cally driven ammonia compressor of 15 tons daily refrigerating 

 capacity. Its control is automatic, the temperature being regulated 

 at the switcliboard. 



The double-pipe ammonia condensers are in two series of 12 pipes 

 each and 19 feet 6 inches in length. The outer tubes are of 2-inch size, 

 the inner li/^-inch. The refrigerating tank is 14 feet long. 4 feet 

 wide, and 5 feet deep. It carries four stacks of 114-inch galvanized 

 pipe, 14 feet long, making a total of 1.600 feet of pipe. The am- 

 monia-receiving tank is 7 feet long, with a diameter of 16 inches, 

 holding 250 pounds of ammonia. The plant as a whole is known 

 as the " direct-expansion " system. 



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