What expansive wastes of rich productive land lie in this region unheeded by man! Populous though the river banks are, they are but slightly disturbed by labour--a trifling grubbing of parts of the foreshore, a limited acreage for manioc, within a crater-like area in the bosom of the dark woods, and a narrow line of small cotes, wherein the savages huddle within their narrow circumference. One of my amusements in the boat was to sketch the unknown course of the river--for as the aborigines disappeared like rats into their holes on one's approach I could gain no information respecting it. How far was it permissible for me to deviate from my course? By the river I could assist the ailing and relieve the strong. The goods could be transported and the feeble conveyed. Reserves of manioc and plantain could also be carried. But would a somewhat long curve, winding as high as some forty or fifty geographical miles north of our course, be compensated by these advantages of relief of the porters, and the abundance of provisions that are assuredly found on the banks? When I noted the number of the sick, and saw the jaded condition of the people, I felt that if the river ascended as far as 2° N., it was infinitely preferable to plunging into the centre of the forest. The temperature of the air during the clouded morning was 75°, surface of the river 77°. What a relief it was to breathe the air of the river after a night spent in inhaling the close impure air in the forest by night! On the 16th we possessed one boat and five canoes, carrying seventy-four men and 120 loads, so that with the weight of the boat sections, half of our men were relieved of loads, and carried nothing every alternative day. We passed by the mouth of a considerable affluent from the south-east, and camped a mile above it. The temperature rose to 94° in the afternoon, and as a consequence rain fell in torrents, preceded by the usual thunder roars and lightning flashes. Until 1 P.M. of the 17th the rain fell unceasingly. It would have been interesting to have ascertained the number of inches that fell during these nineteen hours' rain-pour. Few of the people enjoyed any rest; there was a general wringing of blankets and clothes after it ceased, but it was some hours before they recovered their usual animation. The aborigines must have been also depressed, owing to our vicinity, though if they had known what wealth we possessed, they might have freely parted with their goats and fowls for our wares. The column camped at 3 P.M. opposite the settlement of Lower Mariri. Besides their immense wooden drums, which sounded the alarm to a ten-mile distance, the natives vociferated with unusual powers of lung, so that their cries could be heard a mile off. The absence of all other noises lends peculiar power to their voices.