the light should pass through the surface of the water. The front towards the room and the observer was constructed of plate glass, the whole being set in a stout framework of zinc, and cemented with what is known under the name of Scott's cement, and which I have found to answer for the purpose most admirably. Within this tank were arranged several large pieces of rock-work, thrown into an arched form, and other fragments were cemented in places against the slate at the back and ends, and at parts along the waterline, so that the creatures could hide themselves at pleasure; a short beach of pebbles was also constructed in order that shallow water could be resorted to if desired. The whole tank was covered with a light glass shade to keep out the dust, and retard evaporation.
"With the sea water obtained in January, 1852, I have been working without cessation up to the present time, agitating and aërating when it became foul during the unsuccessful experiments on the seaweeds, but since then it has been rarely ever disturbed; the loss which takes place from evaporation being made up, as before stated, with rain or distilled water."
My own experiments with marine animals and plants were commenced about the same time as Mr. Warington's, namely, at the end of January, 1852. I was not aware till long afterwards that either that gentleman or any one else had proposed to effect such an object, which had been occupying my mind for some time. My success, which was less perfect than Mr. Warington's, I published in the "Annals of Natural History" for October, 1852, and subsequently, in my "Rambles on the Devonshire Coast." Travel-
