THE FRESH-WATER AQUARIUM. 15 
from ten inches to twenty inches in diameter, and the 
prices from one to fifteen shillings. For general pur- 
poses of use and ornament, I should recommend vessels 
of from twelve to eighteen inches. Those below twelve 
inches are too small to be of much service, and those 
above eighteen are liable to fracture on the: occasion 
of any sudden change of temperature, especially in 
winter. Messrs. Phillips have lately, at my suggestion, 
produced a bell-glass expressly for aquarian purposes ; 
those in use hitherto were made for gardening purposes, 
and were carelessly blown. The shape I have suggested 
is one nearly approaching to that of the blossom of the 
great bearbind, the sides of the vessel describing straight 
