_Rivers._--The principal physical features of British Guiana are its rivers and their branches, which form one vast network of waterways all over it, and are the principal, indeed practically the only, highways inland from the coast. Chief among them are the Waini, the Essequibo, and its tributaries the Mazaruni and Cuyuni, the Demerara, the Berbice and the Corentyn. The Essequibo rises in the Acarai Mts., in 0 deg. 41' N. and about 850 ft. above the sea, and flows northwards for about 600 m. until it discharges itself into the ocean by an estuary nearly 15 m. in width. In this estuary are several large and fertile islands, on four of which sugar used to be grown. Now but one, Wakenaam, can boast of a factory. The Essequibo can be entered only by craft drawing less than 20 ft. and is navigable for these vessels for not more than 50 m., its subsequent course upwards being frequently broken by cataracts and rapids. Some 7 m. below the first series of rapids it is joined by the Mazaruni, itself joined by the Cuyuni some 4 m. farther up. It has a remarkable course from its source in the Merume Mountains, about 2400 ft. above the sea. It flows first south, then west, north-west, north, and finally south-east to within 20 m. of its own source, forming many fine falls, and its course thereafter is still very tortuous. In 4 deg. N. and 58 deg. W., the Essequibo is joined by the Rupununi, which, rising in a savannah at the foot of the Karawaimento Mts., has a northerly and easterly course of fully 200 m. In 3 deg. 37' N. the Awaricura joins the Rupununi, and by this tributary the Pirara, a tributary of the Amazon, may be reached,--an example of the interesting series of _itabos_ connecting nearly all S. American rivers with one another. Another large tributary of the Essequibo is the Potaro, on which, at 1130 ft. above sea-level and in 5 deg. 8' N. and 59 deg. 19' W., is the celebrated Kaieteur fall, discovered in 1870 by Mr C. Barrington Brown while engaged on a geological survey. This fall is produced by the river flowing from a tableland of sandstone and conglomerate into a deep valley 822 ft. below. For the first 741 ft. the water falls as a perpendicular column, thence as a sloping cataract to the still reach below. The river 200 yds. above the fall is about 400 ft. wide, while the actual waterway of the fall itself varies from 120 ft. in dry weather to nearly 400 ft. in rainy seasons. The Kaieteur, which it took Mr Brown a fortnight to reach from the coast, can now be reached on the fifth day from Georgetown. Among other considerable tributaries of the Essequibo are the Siparuni, Burro-Burro, Rewa, Kuyuwini and Kassi-Kudji. The Demerara river, the head-waters of which are known only to Indians, rises probably near 5 deg. N., and after a winding northerly course of some 200 m. enters the ocean in 6 deg. 50' N. and 58 deg. 20' W.