LAST winter quite a little excitement was caused among a party of skaters on the Serpentine River, England, by one of the party making a lens of ice and lighting the pipes of the others. This brings to mind the fact that this curious experiment was first brought before the public by Dr. Scoresby, who, when in the polar regions, to the great astonishment of his companions, who did not understand why the ice did not freeze the polar rays, performed the same remarkable feat. It may also be worthy of remark that Professor Tyndall, when a tutor in the Royal Institution, on several occasions set fire to little heaps of gunpowder with rays from an electric arc concentrated upon the powder by a lens of ice. His explanation was that, although ice absorbs rays of certain waves of light and is gradually melted thereby, other waves do not absorb, and these latter produce the heating effect at the focus of the lens. It is wholly a question of the relative motions of the molecules of frozen water and the motion of the waves of light.—Selected.