310 THE WORLD'S LUMBER ROOM. 



to be seen in the neighbourhood of smelting furnaces. 

 Sometimes it is crushed and used for concrete walls, but 

 large quantities now lying idle might be employed for 

 making bye-roads, for foundations, macadamising, and as 

 railway ballast. 



Of late, however, it has been applied to a novel purpose. 

 Air is blown into it while it is in a molten state, and 

 the effect is to draw it out into exceedingly fine fibres, as 

 fine as the finest spun glass, and as soft as cotton. It is, 

 in fact, a species of glass, though no one would guess it 

 from its original appearance, and it is used for covering 

 boilers. 



In the Sandwich Islands the birds make their nests ot 

 a similar substance, made not by any artificial means, 

 but by the great volcano, Manna, which churns its 

 molten lava so violently that the spray is dashed high 

 in the air, and, cooling as it falls, forms threads of fine- 

 spun green glass, called by the natives " Pele's hair," which 

 drifts away with the wind, and hrn^s in masses about 

 the trees and rocks. 



