FROST-FORMS ON ROAN MOUNTAIN. 



35 



B 



W- 



FiG. 8. 



ent force was exhibited at the close of the storm of January 6th 

 to 8th, in a recess where a north wing joins the main hotel build- 

 ing. The speed of the wind varied from forty to sixty miles an 

 hour during those three days, and the temperature was from fif- 

 teen to thirty degrees below zero. 



Fig. 8 presents a sketch of the outlines. A B is the northwest 

 corner of the main building, three stories high. C is two stories 

 high, and E D one story. 

 F shows the direction of 

 the wind, which varied lit- 

 tle. A, B, D, and E had 

 heavy, deep cornices of 

 long, narrow plumes like 

 pampas grass, averaging 

 sixteen inches in length, 

 inclined outward from 

 base to tip at an angle of 

 thirty degrees to the plane 

 of the wall, and lying in 

 a horizontal position. The 

 plumes on A and E pointed 

 north by northwest ; those 



on B, west by northwest ; all as directly toward the wind as was 

 allowed by the laws governing their application to the walls and 

 by the angles at which the wind struck the walls. Those on D, 

 being formed by the rebound from the high wall C and the angle 

 C B, pointed east, or toward C, though in all other respects simi- 

 lar to the others. On the weatherboards of A, B, and E the frost- 

 feathers were short and broad. They stood vertically, with their 

 bases on the edges of the boards, each row overlapping the row 

 above, and each row formed by the downward rebound of par- 

 ticles from the thick edge of the board above it. The forms on 

 all the upright corner boards (or facing boards) seemed to have 

 been made later than those on the weatherboards, since they 

 lay horizontally, with their tips pointing toward those on the 

 weatherboards, and at a right angle to them. They must have 

 been made by the rebound from the forms on the weatherboards, 

 as their direction in every instance was exactly opposite to that 

 of the cornice decorations on the same wall. After the first few 

 hours it was impossible to brave the fury of the storm to watch 

 the process of development, which is inferred from the results 

 and the proved rules by which the work is done. 



The forms on the weatherboards of D hung downward, while 

 those on the opposite wall, B, stood upright. This must have 

 been due to the rotary motion of the wind after it struck the 

 three-story wall B and the two-story wall C, and, whirling down- 



