From Central Zungomero to the nearest ascent of the Usagara Mountains is a march of five hours. The route, emerging from the cultivated districts, leaves to the right the Wigo Hills, so called, probably, from the fishing weirs in the stagnant waters below, and in the Mgeta River, which flows through the plain. On the left, and distant four or five miles, is a straggling line of low cones: at the foot of one, somewhat larger than its neighbours, rises the thermal spring known to the people as the Maji ya W’heta, the Geyser, jetting-water, or _fontaine qui bouille_. Its position is a gentle slope between the hill-base and a dwarf Savannah which is surrounded by high walls of jungly forest, and the water-shed is from south to north. The hot water boils and bubbles out of a white sand, here and there stained and encrusted with oxide of iron. Upon the surface lie caked and scaly sheets of calcareous tufa, expressed by the spring, and around it are erratic boulders blackened probably by the thermal fumes. The earth is dark, sometimes sandy, and sprinkled over with fragments of quartzite and sandstone; in other places a screen of brab-tree backs a bold expanse of ground, treacherous, boggy, and unstable as water. The area is about 200 feet in diameter, and the centre of ebullition is unapproachable, owing to the heat and the instability of the soil. According to the guides, it is subject to occasional eruptions, when the water bursts out with violence, and fragments of lime are flung high in the air. Animals are said to refuse it, and tales are told of wild beasts having been bogged in the seething mire.