8 



Machinery. 

 Not the least important (lejiarf inent of the Aquarium is the Machinery-room. 

 liiu,i>' of tlie estal)lishmeiit in tlie shape of a'ForcFs air-eompressor, whi(" 

 up to a ]iressni-e of 15n Ihs. to the square inch, and Avliich is stored in two cylinders 



g;>'i ^ - ' 



Here is the 



1 condenses atmosjjhere 



or receivers. 



lilKliUMIM St Kl '^ \r lllh ^IJCAltir.M. 



;W feet h:)n<;- and 3 feet iu diameter. This is one of the features ol this Aquarium, and renders it 

 distinct from all otliers, where a constant stream of water has to he kept runninj;- tlirouu'h to the 

 tanks, as the air is regulated by a system of pressure-gauges, and the attendant, on leaving in the 

 afternoon, simjily sets his taps, and the air is supplied in proper quantities till the next 

 morning. 



In order to assist in maintaining the proper condition of the tanks, the water is circulated 

 for an hour or more every morning, a separate stream heing poured into each tank aud carried off 

 by overflow ])i]ies. 



The following note from the report of the Director of the Marine Biological Association^ 

 Plymouth, explains the system adopted in their Laboratory, which is similar to ours, with this 

 difference, that they have the advantage of a daily supply of salt water from the sea, which we 

 do not enjoy at the Exhibition Aquarium. 



