Note 155 — Chapter XVIII
Reading edition
The average temperature of the water in the Lower Amazon is 81°, that of the air being a little less. The temperature of the Huallaga at Yurimaguas was 75° when the air was 88° in the shade; in another experiment both the river and air were 80°. The Marañon at Iquitos was 79° when the air was 90°. At the mouth of the Juruá, Herndon found both water and air 82°. In the tropics the difference between the temperature of the water and air is proportionally less than in high latitudes.