A launch of considerable size, towing a house-boat provided for first-class passengers, left Rockstone early the following morning. The Essiquibo is truly a very great river, and the height and magnificence of the forest covering its banks is not exceeded in any part of South America. In some instances, the trees are one hundred and seventy-five feet high; cottonwood, greenheart, and wallaba mingled their leafy crowns far above the mere rabble of palms and lower growth, shutting out the light and effectively killing their competitors until--after hundreds of years of successful fighting--the strain begins to tell and the monarchs are compelled to bow before the inevitable onslaught of old age. At the first signs of weakness enemies spring up on every side. The struggle for life is constant and in deadly earnest. Of the hundreds, perhaps thousands, of saplings which appear as the light and air gradually penetrate through the opening made by the dying giant, only one can eventually survive. Naturally, the strongest and fittest possesses every advantage in the mad fight for existence, and as it quickly outstrips its weaker rivals they wither and die. The launch called at a number of rubber-plantations and lumber-camps. Great quantities of greenheart (_Nectandra rodiæi_) are cut and exported; the wood is very hard and durable, and resists decay when under water, for which reason it is used largely for submerged work such as wharfs and piles. Next in importance is crab-wood (_Carapa guianensis_) employed in building houses; third in value are several varieties of wallaba (_Eperua_); this wood has a coarse but even grain and is very resinous, being suitable for the manufacture of shingles and vat-staves. The rubber industry ranks third in importance in British Guiana. By far the greater part of this product is balata, collected from indigenous trees that are tapped under careful government supervision. _Sapium_ yields the better quality of rubber, but exists in limited quantities only, and the majority of the trees on plantations have not yet reached the productive age. Our first headquarters were made at Tumatumari, a short distance above the mouth of the Potaro River. The river is at this point encumbered with a series of rapids ending in a fall of twenty or thirty feet. [Illustration: Wismar on the Demerara River.] [Illustration: Tumatumari on the Potaro River.]