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. 
