MY OWN TANK
As the principal subject of these pages is the Marine Aquarium, including, and indeed subsidiary to, the history of the plants and animals which it enables us to keep under our observation, it may not be impertinent in me to give some account in detail of my own. Hitherto I had contented myself with cylindrical glass vases, ten inches in height and five in diameter, which answer admirably for small objects; with wide shallow pans of yellow and white ware; and with a foot-bath of the latter. These, though affording opportunity for many interesting observations, were deficient in some points, which would be supplied by a Tank of ampler dimensions, with parallel sides to prevent unequal refraction and consequent distortion, and made wholly of plate-glass to allow distinct vision in every part.
Such a vessel I have had made under my own direction; and as it will be the chief medium of most of the notes that occur in the subsequent pages of this work, I will describe in detail its dimensions, form and structure; the mode in which I filled and stocked it; with some accounts of failure and disappointment to serve as beacons, as well as of success to stimulate with encouragement. I do not hold it up as a perfect example, but as an essay actually made, "with all its imperfections on its head."
The tank is 2 feet long, 112 foot wide, 112 foot deep; the sides and ends of 316ths plate-glass; the bottom of slate; the corners of birch-wood, turned into pillars, each surmounted by a knob, and united by a frame top
