THE PUBLIC AQUARIUM 273 



live in it. Such deterofiation as takes place is counteracted to some 

 extent by the occasional additions of pure sea water of ocean 

 salinity. 



As the New York Aquarium makes exchanges of marine animals 

 for fresh-water species of other aquariums, the reservoir supply neces- 

 sarily is drawn upon for water used in shipment. This procedure, 

 which necessitates small annual additions of pure sea water, is helpful 

 in maintaining the purity of the stored supply. New supplies of sea 

 water are obtained by sending a tank boat outside the harbor to be 

 filled on a rising tide. For this purpose tank boats engaged in sup- 

 plying merchant vessels with fresh water are available. 



The undergi'ound reservoir of the New York Aquarium was 

 installed in 1908 after experience had shown that the brackish and 

 sewage-laden water pumped from the harbor was not suitable for the 

 keeping of marine animals. The original supply of stored sea water 

 has been in use ever since. This reservoir, which is of reinforced 

 concrete and 100,000 gallons capacity, is divided into four adjoining 

 chambers of equal size, connected with each other by valve-controlled 

 equalizing pipes. Water returning from the filters is discharged into 

 the first of the series and pumped from the last. A small central 

 valve chamber is equipped so that water may be pumped from and 

 returned to any desired combination of the four chambers. As any 

 three of the reservoir chambers may be made to hold all of the supply 

 of water, it is possible to empty them in turn for such cleansing as 

 may be necessary. This has been found necessary only seldom, 

 apparently owing to the constant filtration of returned water. 



A reservoir should be of sufficient capacity to hold at least twice the 

 quantity contained in tlie entire series of exhibition tanks that it 

 serves. A large supply gives the body of water in the reservoir more 

 opportunity for precipitating the finer particles of matter in suspen- 

 sion. In winter the necessary temperature can be maintained to 

 better advantage with a large body of water. The location of the 

 22.000-gallon reservoir of the new Bermuda aquarium, which supplies 

 27 tanks, is located above the level of the exhibition tanks and 30 feet 

 above sea level. 



In the construction of the reservoir precautions should be taken 

 against leaks, which may eventually entail expense for renewals. In 

 the course of time the concrete walls and bottom of the New York 

 Aquarium have developed minute leaks, which caused a somewhat 

 greater loss of water than could be accounted for otherwise. It 

 finally became necessary to empty the sections of the reservoir in 

 turn and make repairs. In several places the concrete was found to 

 have deteriorated. 



An analysis of the long-stored water supply was made in 1927, 

 which showed it little changed except that its alkalinity had dis- 

 appeared and the high nitrate (70.00) had accumulated by oxidation 

 of the nitrogenous refuse of the fishes. The most effective procedure 

 under the circumstances was believed to be the renewal of the entire 

 supply, and accordingly this was done. 



The aquarium at Naples, Italy, renews the supply of stored water 

 occasionally at favorable times when the water of the bay is clearest. 

 At Plymouth, England, it is renewed every six months, pumping 



