292 AT SEA. 



midsummer thunder-clouds that had retired from 

 business ; the captains of the storm in easy undress. 

 All day they filed along there, keeping the ship com- 

 pany. How the eye reveled in their definite, yet 

 ever-changing, forms ! Thejrjjja^er or base line was 

 as straight and continuous as the rim of the ocean. 

 The substratum of air upon which they rested was 

 like a uniform layer of granite rock, invisible, but 

 all-resisting; not one particle of these vast cloud- 

 mountains, so broken and irregular in their summits, 

 sank below this aerial granite boundary. The equi- 

 librium of the air is frequently such that the under 

 surface of the clouds is like a ceiling. It is a fair- 

 weather sign, whether upon the sea or upon the land. 



e may frequently see it in a mountainous district, 

 when the fog-clouds settle down, and blot out all the 

 tops of the mountains without one fleck of vapor go- 

 ing below a given line which runs above every val- 

 ley, as uniform as the sea-level) It is probable that 

 in fair weather the atmosphere always lies in regular 

 strata in this way, and that it is the displacement 

 and mixing up of these by some unknown cause that 

 produces storms. 



As the sun neared the horizon these cloud masses 

 threw great blue shadows athwart each other, which 

 afforded the eye a new pleasure. 



Late one afternoon the clouds assumed a still more 

 friendly and welcome shape. A long, purple, irreg- 

 ular range of them rose up from the horizon in the 

 northwest, exactly simulating distant mountains. The 



