Note 13 — Chapter II
Reading edition
September to January is the hottest portion of the year, the heat being at its worst in December. 90° would be extreme heat, and 70° the lowest the mercury would probably reach; the average being from 75° to 85°. Robuchon is responsible for the statement that the temperature at the mouth of the Cotuhe in September was 43° Cent. in the shade, but that after a brisk shower it fell to 31°. The water of the Amazon has a temperature of 81°; the Japura is a warmer river and reaches 85°. Wallace gives the mean temperature of the Rio Negro water in September—that is, during the hot season—as 86°, and the corresponding temperature of the air as from 76° to 92.5°. The water, he considers, is probably never less than 80° at any time. The temperature of the Uaupes has been noted as invariably 76° at three to six feet below the surface (Geo. Journ., 1910, p. 683).