THE CLOUD REGION, ETC. 277 



have to cross it. Tliey are often baffled in it for two or three 

 weeks ; then the children and the passengers who are of delicate 

 health siiifer most. It is a frightful graveyard on the waj^side to 

 that golden land. A vessel bonnd into the southern hemisphere 

 from Europe or America, after clearing the region of variable 

 winds and crossing the " horse latitudes," enters the north-east 

 trades. Here the mariner finds the sky sometimes mottled with 

 clouds, but for the most part clear. Here, too, he finds his 

 barometer rising and falling under the ebb and flow of a regular 

 atmospherical tide, which gives a high and low barometer every 

 day with such regularity that the hour within a few minutes 

 may be told by it. The rise and fall of this tide, measured b}^ 

 the barometer, amounts to about one-tenth (0.1) of an inch, audit 

 occurs daily and everywhere between the tropics : the maximum 

 about 10 h. 30 m. a.m., the minimum betAveen 4 h. and 5 h. p.m., 

 with a second maximum and minimum about 10 p.m. and 5 a.m.* 

 The diurnal variation of the needle (§ 344) changes also with the 

 turning of these invisible tides. Continuing his course towards 

 the equinoctial line, and entering the region of equatorial calms 

 and rains, the navigator feels the weather to become singularly 

 close and oppressive ; he discovers here that the elasticity of 

 feeling which he breathed from the trade-wind air has forsaken 

 him ; he has entered the doldrums, and is under the " cloud- 

 ring." 



515. A frigate under the cloud-ring. — I find in the journal of the 

 late Commodore Arthur Sinclair, kept on board the United 

 States frigate Congress during a cruise to South America in 

 1817-18, a picture of the weather under this cloud-ring that is 

 singularly graphic and striking. He encountered it in the 

 month of January, 1818, between the parallel of 4° north and 

 the equator, and between the meridians of 19^^ and 23^^ west. He 

 says of it, " This is certainly one of the most unpleasant regions 

 in our globe. A dense, close atmosphere, except for a few hours 

 after a thunderstorm, during which time torrents of rain fall, 

 when the air becomes a little refreshed ; but a hot, glowing sun 

 soon heats it again, and but for j^our awnings, and the little air 

 put in circulation by the continual flapping of the ship's sails, it 

 would be almost insufferable. No person who has not crossed 

 this region can form an adequate idea of its unpleasant effects. 



* See paper on Meteorological Observations in India, by Colonel Sykes, 

 riiilosophical Transactions for 1S50, part ii., pngo 297. 



