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What Is Hoarfrost? 



IN every-day English the word "rime" 

 is synonymous with "hoarfrost" and 

 is apphed to the fine white deposit which 

 replaces dew in cold weather. Hoarfrost 

 is sometimes defined as "frozen dew," 

 but it is more often a direct deposit of 

 small ice crystals from the atmosphere, 

 the invisible water vapor turning to ice 

 without passing through the liquid form. 

 In recent technical literature the term 



Popular Science Monthly 



Hoarfrost is a powerful but 

 mischievous magician. Above, 

 a beautiful effect created on a 

 tree; on the right, a wire rope 



"rime" has a different 

 meaning. It is limited in 

 its application to those 

 striking deposits of rough 

 ice or of feathery crystals 

 which sometimes form on exposed 

 objects surrounded by fog, when the 

 temperature is below freezing. This 

 formation is, in its turn, distinguished 

 from the smooth coating of ice which 

 results from rain in cold weather, and 

 to which the name "glazed frost" is now 

 applied. Heavy deposits of glazed frost 

 often load branches, wires, etc., to the 

 breaking point, and give us the familiar 

 phenomenon of an "ice storm." 



Of all these various frost deposits, 

 true rime perhaps presents the most curi- 

 ous forms, and these reach their fullest 

 development on mountain summits and 

 in the polar regions. Beautiful tufts 

 and fringes of ice form on objects of 

 small diameter, such as twigs and wires, 

 and along the angles of square posts and 

 the like, but not on broad sur:^ces. The 

 deposit is almost or quite confined to 

 the windward side, and grows against 

 the wind. 



At the former meteorological observa- 

 tory on Ben Nevis these ice feathers 

 were sometimes seen to grow at the rate 

 of two inches an hour. In the winter 

 of 1884-5, according to Mr. R. T. 

 Omond, "during a long continuance of 

 strong southwesterly winds and cold 

 weather a post four inches square grew 

 into a slab of snow some five feet broad 

 and one foot thick in less than a week ; 

 the crystalline mass then fell off by its 

 own weight and a new set began to 

 form." 



The anemometers and other 

 out-of-door instruments at the 

 observatory were generally so 

 coated with rime in winter as to 

 be useless. 



T' 



A Curious Tobacco 

 Pipe-Borer 



RAVELERS among the 

 Sioux Indians are very 

 much impressed with the per- 

 fect smoothness of the bore in 

 their pipe-stems. Without the 

 use of a tool of any kind, they 

 make a perfect bore in the twigs 

 of ash trees, which they use for 

 musical instruments and for 

 pipes. To accomplish this end, 

 they employ the larva of a but- 

 terfly which inhabits the ash 

 The Indians remove the pith for 

 about three inches from the stick they 

 wish bored. Into this cavity, they place 

 one of the larvse of a brown butterfly, 

 which gradually eats its way down 

 through the pith until the bore is com- 

 pleted. A little heat applied to the wood 

 expedites the work of the larvse. The 

 Indians consider both the tube made in 

 this way and the larva as sacred as their 

 idols. 



tree. 



