CAPILLARY WAVES. 449 



a mile an hour, and the glassy smoothness dis- 

 appears, but on its departure the surface re- 

 mains polished as before. By and by this fitful 

 movement of the air .becomes regular, and the 

 mirror -like appearance is permanently lost ; 

 the surface is covered with countless wavelets, 

 and we have the phenomenon of capillary waves 

 produced. Still, any sheltered spot, where the 

 direct action of the wind is not felt, has the 

 same mirror-like surface at first possessed by 

 the whole, for these waves cease almost instan- 

 taneously upon the intermission of the disturb- 

 ing cause, not being able to travel spontaneously 

 to any considerable distance. The disturbed 

 surface now presents that appearance of black- 

 ness which is often justly regarded as the pre- 

 cursor of a storm. This results from the effect 

 of the unevenness of the surface upon the re- 

 flection and refraction of light. 



The wind still rises ; the increasing clouds 

 gather blackness, and nature is overspread with 

 a certain indefinite appearance of gloom, which 

 is often the sure harbinger of a tempest. The 

 movement of the air is now not less than two 

 miles an hour. Small waves begin to rise uni- 

 formly over the whole surface of the water with 

 great regularity. On the ridges of these waves 

 the tiny capillary waves are seen riding, but as 

 the wind increases they disappear, and are then 



2 G 



