FEBRUARY. 451 



niglit after mild and thawing weather on the preceding 

 day. Nothing in the world seems so much like the effects 

 of enchantment. The pictures made by the frost upon 

 our window-panes are a part of the domestic scenery of 

 winter; but their origin and progress form a curious study. 

 It is remarkable that this deposit of frost resembles in 

 structure and development the formation of clouds in 

 clear weather in the upper region of the heavens. The 

 clouds usually display more beauty of form in winter and 

 in very dry weather, because the arid state of the atmos- 

 pliere is favorable to tlieir delicate organization. Hence 

 the most beautiful clouds are those which are highest 

 above the earth's surface, where the air contains but very 

 little moisture. The same principle affects the formation 

 of window-frost. The air of the room when only slightly 

 charged with vapor projects the most delicate and beauti- 

 ful figures on the windows. 



The first deposit on the window-glass, when the weather 

 is very cold and the air of the room moist, is a thin iri- 

 descent film resembling that produced by oil spread upon 

 the surface of still water. This iridescence vanishes at 

 the moment when the film begins to change into a crys- 

 tallized surface. Immediately there appears in the place 

 of it a collection of little flocculi, — a sort of constellation 

 of minute snow-flakes, without any formal arrangement. 

 These, as they increase from the moisture of the room, 

 slowly assume a feathery organization, with more or less 

 geometrical beauty, according as the deposit is made from 

 air that is lightly or heavily charged with dampness. The 

 less the moisture in tlie air of the room, if there be a 

 sufficient quantity, and the colder the air outside if the 

 inner air be not much above freezing-point, the finer and 

 more beautiful are these configurations. Hence the win- 

 dows of a sleeping-room, if not occupied by more than 

 two or three persons, are more delicately frosted on a cold 



