��Popular Science Monthly
���Yr^AtZ IrK "^^"'^^l^i^E;, These beautiful deposits assume two principal forms, the feathery
Sd iesi.n ?hf "'• ^^" ^""TV ^^' ™°^^ ^°"^"^°" ^"d the more striking in appearance ana design. The same pane of glass will exhibit entirely different designs on different nights
��exists at all times in the air, and not from raindrops; though, on the other hand, rain IS often the final product of snow that melts before it reaches the ground.
The true structure of a mass of ice may, however, be made evident by an experiment that Tyndall was fond of performing in his public lectures. Through a slab of clear ice, revealing no trace of structure, he passed the beam of an electric lamp, the light falling upon a screen. The image of the slab was magnified by a lens. While the
��light of the lamp was transmitted freely, its heat was partly absorbed by the ice, and produced an interesting transforma- tion. _ Numerous six-rayed stars and com- binations of such stars appeared here and there on the screen. These "ice-flowers," as they are called, resulted from the melt- ing of crystals locked up in the block of ice; they were, in fact, hollow spaces, retaining the form of the original crystals but filled with water.
The invisible moisture of the air produces