Page:Popular Science Monthly Volume 90.djvu/39

 The Wonderworld of Ice Crystals

More than a thousand different forms. You can study many of them at home with a magnifying glass

���b.veb was frst strung with dewdrops, which froze to globules of ice as the air grew colder. This is one form of hoarfrost, but lacks the interest of the crystalline forms

��WHEN winter settles down upon the earth, a new artist appears upon the scene. Hardly less varied and not a whit less exquisite than the products of the vegetable kingdom are the flower-like wonders of ice, snow and hoarfrost. If their beauty is not fully appreciated, it is because a close inspection is needed to reveal it. In fact, whoever would feast his eyes on the crystal marsels of the frosty countryside, or of his own windowpane, needs to be provided with a good magnify- ing glass, or he will miss half the show.

The study of ice crystals has an interest- ing histor\-, beginning with the works of Albertus Magnus, who gravely informs us that "star-like snow" falls only in February and March. The earliest drawings of snow cr>stals and also of frostwork on window- panes were made by the learned Arch- bishop of Upsala, Olaus Magnus, in the middle of the sixteenth century.

A new era has, however, been introduced

��in our own time in this class of investiga- tions by the application of photography to the subject. Today more than a thousand diff^erent forms of snow and ice cr^-stals may be studied in collections of "micro- photographs." One of the facts revealed by the camera is that the perfectly regular forms of these crystals shown in drawings are comparatively uncommon in Nature. When a cr\-stal is originally formed it is, un- doubtedly, perfectly symmetrical, but it is so fragile that it is easily mutilated by the wind and by contact with other crystals. In very calm weather, at the beginning of a snowstorm, many single and perfect crystals are wafted gently to earth, and such cr>'stals may also be seen floating in the air in the intense cold of the polar regions, constituting the sparkling ice-haze, known to explorers as "diamond snow," or "diamond dust."

Snow is produced directly from water vapor (i. e., water in a gaseous state) that

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