547 



A 94° 623 

 C 95° 112 

 F 96° 0 



4<r Atnoon the depression of the horizon is still 96° 1. 

 Dead calm. 



" On the 25th and 26th of September, the horizon, shining 

 with light, oscillating three or four times in the space of an 

 hour. The depression of the horizon is sometimes 95° 118, 

 sometimes 90° 4, without any change in the meteorological 

 instruments, in the place where Bird's quadrant is. The 

 changes no doubt take place in the intermediary strata of air, 

 and in the temperature of the water and of the ground, which 

 radiate heat. I think 1 perceive, that the changes of de- 

 pression are announced by a variation of colour. Without 

 any alteration in the azure colour of the sky, the horizon of 

 the sea separates into two bands. I see a streak of a deeper 

 colour than the rest ; all that is farther off than this streak 

 grows paler, and at length completely disappears ; and all 

 that is nearer than the streak acquires a deeper colour. The 

 island of Picuita is already suspended. It's foot (it's inferior 

 limit) does not change ; but progressively, as the streak be- 

 comes the horizon, and as that part of the sea behind the 

 streak disappears, the apparent suspension of the island 

 augments. It seems to retire farther off from the hori- 

 zon 5 while it is rather the horizon, that has retired from 

 the island. Before the formation of the streak : D. 95° 116 8, 

 F. 95° 119. A quarter of an hour later, after the zone 

 behind the streak has become invisible, I find D. 95° 116* 3, 

 F. 96° 4*8. By degrees the anterior zone, which forms 

 the horizon, grows paler in it's turn, and the portion of sea 

 behind the streak reappears. You would say, that this gains 

 in colour what the other loses. F. is again 95° 118. D. 

 remains invariably 95° 116*5. The part which has reap- 

 peared acquires a deep blue tint : the nearer part, on the 

 contrary (that which formed the horizon, when the depression 



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