ZOOLOGICAL PARKS AND AQUARIUMS 931 



riums in various parts of the world to which the public is admitted, exclusive 

 of several very small ones connected with biological laboratories. 



It has long been the custom of the National Bureau of Fisheries to 

 operate large temporary aquariums at American industrial expositions, and 

 these splendid governmental exhibits have been successful in the highest 

 degree. It is a remarkable fact that at the world fairs of Chicago, St. Louis, 

 Buffalo, Omaha, Charleston, Nashville and Portland, the government aqua- 

 rium attracted in each case more visitors than any other single exhibit 

 of the exposition. The larger permanent aquariums of the world attract 

 the attention and patronage of the people to a greater extent than that 

 usually directed toward the zoological garden or the museum of natural 

 history or art. 



The living collections of the larger public aquariums consist usually 

 of both marine and fresh-water animals. It is the character of the exhibits, 

 whether of marine or fresh-water forms, which determines the cost of 

 maintenance in an institution of this kind. An aquarium with exhibition 

 tanks requiring nothing more complicated than mere connections with a 

 city water system, can obviously be operated at less expense than one 

 requiring pumps for the circulation of sea water. It would be possible for 

 any inland city not too remote from lakes or rivers to maintain excellent 

 collections of fresh-water fishes and amphibians at small cost as compared 

 with marine exhibits requiring stored sea water. The flow of fresh water 

 being practically automatic, the equipment for operation can be reduced 

 to very simple terms. With the introduction of marine exhibits, the equip- 

 ment, management and cost of maintenance would be altogether different. 

 The piping, if for permanent use with salt water, would be specially con- 

 structed of vulcanized rubber or other non-rusting material, with fittings 

 to match. An underground reservoir for the storage of sea water would 

 be necessary, together with rust-proof pumps of bronze for its circulation. 

 Filters would be required for the clearing of the water constantly flowing 

 back to the reservoir. With the use of steam pumps which must run night 

 and day, there would follow an increase in the number of employees, some 

 of them being mechanicians requiring special compensation. If tropical 

 forms of life were added, water-heating equipment would be required to 

 ensure their safety in winter. In connection with the matter of warm water 

 for tropical exhibits in winter, it should be noted that cold water is equally 

 necessary for northern forms of life in summer. A large aquarium in the 

 latitude of New York, for instance, requires a decidedly complicated equip- 

 ment if its aquatic exhibits include both northern and tropical, fresh- 

 water and marine forms. 



The construction of a reservoir for pure sea water is imperative even 



