If you examine it closely the morning after it freezes, you find that the greater part of the bubbles, which at first appeared to be within it, are against its under surface, and that more are continually rising from the bottom; while the ice is as yet comparatively solid and dark, that is, you see the water through it. These bubbles are from an eightieth to an eighth of an inch in diameter, very clear and beautiful, and you see your face reflected in them through the ice. There may be thirty or forty of them to a square inch. There are also already within the ice narrow oblong perpendicular bubbles about half an inch long, sharp cones with the apex upward; or oftener, if the ice is quite fresh, minute spherical bubbles one directly above another, like a string of beads. But these within the ice are not so numerous nor obvious as those beneath. I sometimes used to cast on stones to try the strength of the ice, and those which broke through carried in air with them, which formed very large and conspicuous white bubbles beneath. One day when I came to the same place forty-eight hours afterward, I found that those large bubbles were still perfect, though an inch more of ice had formed, as I could see distinctly by the seam in the edge of a cake.