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6 REPORT ON THE CAOUTCHOUC OP COMMERCE. 
ruary, and March it gradually increased from 5 to 10, till in April 
it reached 15, In May it gradually lessened, till in June and 
throughout the rest of the year it was under 5 inches (Eig. 2). 
The heat not generally above 87° in the afternoon, or below 74° 
at night. The temperature during three years only once reached 
95° (Wallace). The greatest heat is about 2 p.m., from 89° to 94°, 
and never cooler than 73°. The mean for the year, 81° (Bates). 
The Amazon begins to fall in the beginning of June ; at the same 
time the forest trees begin to push out their new leaves, especially 
those of the river margins. The trees of the Gap6 (land inundated 
during the winter) begin to flower as soon as the waters leave them. 
The Amazon is full of islands, and these during the wet season are 
covered with water, i i also is a great extent of low country on 
cither bank. The Amazon begins to rise in December, attains its 
greatest height in March, and least height in July and August. 
The Amazon valley is remarkable for uniformity of temperature 
and for regular supply of moisture. Erom June to December is the 
dry season, and January to May the wet. In the dry season in 
November there are a few occasional showers, and during the wet 
season intervals of fine weather. On the Amazon itself the dews 
are scarcely perceptible, owing piobably to the strong winds which 
almost daily sweep up it (as far a. the mouth of the Eio Negro), 
whilst on the Bio Eamos Dr. Spruce found the dews to be very 
heavy. 
Up the Eio Negro the heat early in the morning is about 75° 
(the temperature of the water 85°, and at neon 86°), increasing at 
noon to 95° to 100°. On the banks are dense moist forests, with 
Caoutchouc trees interspersed. Dr. Spruce, when at Barra, in De- 
cember 1850, found that the rains had set in some weeks previous, 
and from December 10th to the beginning of the following Eebruary 
only a single day occurred without some rain. In Eebruary there 
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