TWENTIETH ANNUAL REPORT 105 



Extensions of piping from the air compressor have been 

 installed in both salt-water filters as an aid in the weekly clean- 

 ing of the sand beds. Installed in the bottom of each filter, these 

 air pipes have proved most serviceable. When the sand beds of 

 the filters are washed by reversing the flow of water, the air 

 and water bubbling up together clean the sand decidedly better 

 than has heretofore been possible. 



During the past year the shipment of tropical fishes was 

 facilitated by the construction of large wooden tanks to be used 

 on board steamships. They are larger than any of the expen- 

 sive galvanized shipping tanks used heretofore and proved to 

 be more satisfactory. There is a decided advantage in carrying 

 each lot of fishes in as large a body of water as possible. 



It is believed that wooden shipping tanks will also last 

 longer. Metal tanks are easily dented and rendered leaky by 

 the rough handling they get on shipboard, while rust attacks 

 them even when galvanized. 



On shipboard it is not always possible to have the shipping 

 tanks carried between decks, and in the cold weather of early 

 spring when tanks are carried on the upper deck, tropical fishes 

 may become chilled. 



The wooden tanks undoubtedly keep the water warmer than 

 it can be kept in metal tanks. This fact alone is a point de- 

 cidedly in their favor. They are, of course, heavier and more 

 difficult to handle, but on shipboard they can usually be hoisted 

 by steam power. The cost of wooden tanks is less than half 

 that of metal tanks of similar size. 



An automatic stereopticon installed in December has proved 

 an attractive exhibit. It carries fifty lantern slides illustrative 

 of aquatic life and the methods of conducting aquarium work. 



Visitors to the Aquarium have taken a decided interest in 

 the splendid model of the proposed enlargement of the building. 

 This model was moved to the Aquarium early in the year from 

 the Museum of Natural History where it was first installed. 



When visitors are informed that the City is not at present 

 disposed to undertake its construction, there are frequent ex- 

 pressions of regret. It might be worth while to call for sub- 

 scriptions from the public. If the public were to take an active 

 interest by subscribing small sums, it is probable that public 

 spirited citizens would come forward with generous donations. 



