CANARY ISLANDS. 31 



and scarcely attained 14° or 15°. " When, instead of di- 

 recting the apparatus to a great extent of open sea, the 

 observer fixes his eyes on a small part of its surface viewed 

 through a narrow aperture, the water appears of a rich 

 ultra-marine color. Towards evening, again, when the 

 edge of the waves, as the sun shines upon them, is of an 

 emerald green, the surface of the shaded side reflects a 

 purple hue. Nothing is more striking than the changes 

 which the color of the sea undergoes under a clear sky, in 

 the midst of the ocean and in deep water, when it may be 

 seen passing from indigo-blue to the deepest green, and 

 from this to slate-gray. The blue is almost independent 

 of the reflection of the atmosphere. The inter-tropical 

 seas are, in general, of a deeper and purer tint than those 

 of high latitudes, and the ocean often remains blue, when 

 in fine weather, more than four-fifths of the sky are cover- 

 ed with light and scattered clouds of a white color." 



At anchor in Quarantine, Port Orotava, ) 

 Thursday, August 15, 1833. \ 



