i6 POPULAR SCIENCE] MONTHLY. 



At the present day it has become a difficult matter to classify 

 the various aquariums of Europe, since they present so wide a 

 range in size, quality, and purpose. Some are destined solely for 

 the public use and can not be said to be of aid to scientific studies ; 

 others are devoted almost entirely to the advancement of biologi- 

 cal research ; and others still vary widely between these extremes, 

 with an equally wide range in the character of their financial 

 support. Many of the aquariums of the orthodox biological sta- 

 tions, however, have been situated in out-of-the-way places, con- 

 venient for the purposes of the student, but inaccessible to the gen- 

 eral visitor. These may be admirably arranged and maintained 

 among them, for example, the aquarium room of the French 

 station at Banyuls, on the Mediterranean, near Spain yet they 

 can not be strictly regarded as belonging to the class of public 

 aquariums. For this reason, partly, more than a score of biologi- 

 cal laboratories might at once be omitted from discussion. On 

 the other hand, the Stazione Zoologica of Naples, while devoted 

 to the highest type of research work, must be given the foremost 

 rank among popular aquariums. And the Amsterdam Aquarium, 

 holding rank on the popular side probably second to Naples, is 

 also of value as a purely scientific station, although lower in caste 

 than the Stazione. So, too, should the Plymouth Biological Labo- 

 ratory be mentioned as of interest in its well-equipped aquarium. 

 Together with those that have just been mentioned, the more 

 strictly popular aquariums of Europe should include those of 

 Paris, Berlin, and Brighton. 



These aquariums are so widely separated from each other that 

 they have come to differ not a little in the details of their equip- 

 ment and management. And it is, indeed, only when the visitor 

 has examined a number of these institutions that he begins to 

 realize that there is a common principle underlying their gen- 

 eral construction. Thus, for example, he would find in each the 

 great darkened corridor, from which on every side, as through 

 large windows, he may look into the brightly lighted tanks. 

 Through these he may peer to a distance of twenty feet before 

 his view is stopped by the rough, rock-cut background ; nor does 

 the line showing the surface of the water appear against the 

 glass to destroy his illusion of ocean depth. The cunning builders 

 have taken pains to have this line higher than the windowlike 

 opening of the tank, so that the water surface, instead of mar- 

 ring the effect, in reality aids it, for the eye of the visitor, at 

 a lower plane than the surface, sees upward but the totally re- 

 flected images of the forms below. Not that the glass fronts of 

 the aquaria are exceedingly large their height is rarely more 

 than four or five feet in view of the danger of breakage through 

 water pressure although the idea of water depth is certainly not 



