330 OUT OF DOORS. 



engines are the heart of the aquarium, and the water is 

 the blood. Under the feet of the visitor is an enormous 

 tank, in which are eighty thousand gallons of sea water, 

 exclusive of the twenty thousand gallons contained in 

 the inhabited tanks. By means of the engine the 

 water is kept perpetually circulating through the upper 

 and lower tanks, while at the same time air is driven 

 forcibly into it, and it is exposed both to the fresh air 

 and to sunshine. Everything is carefully calculated, 

 and even the wooden bridge on which the attendants 

 walk has another use, serving also to keep off the light 

 from the water, and so to discourage the excessive 

 growth of the green algae which are the plague of most 

 aquariums. The consequence of this constant care is 

 that the water is kept bright and clear as crystal, and, 

 though the visitor is surrounded with many thousands 

 of living beings, not the least evil odour is perceptible, 

 the air being as fresh and pure as it is outside the 

 building. 



Uniformity of temperature is also secured, and even 

 during the few broiling days of last year, when the 

 Greenwich register showed 88 degrees in the shade, the 

 temperature of the aquarium was just 20 degrees lower. 

 After all that we have said, can the reader do better 

 than make a long visit to the aquarium, buy a hand- 

 book, and make himself thoroughly acquainted with the 

 world of wonders that lies unknown at our feet as we 

 wander on the seashore ? 



