Presently appear the rains which have followed the northing sun. The same observation was made by the Austrian mission on the White River in N. lat. 4° 30′. On the coast we can distinctly trace their progress. In 1857 the downfall began in Feb. 15, at Usumbara (S. lat. 5°), where the clouds are massed and condensed by a high plateau, leading to lofty, snow-capped mountains. In 1854 I found that the rainy season opened at Berberah of the Somal (N. lat. 10° 25′) on April 15; and in early June they reach Bombay (N. lat. 18° 53′). Concerning the movement of the wet season in inner intertropical Africa I have already written in the Journal of the Royal Geographical Society (xxix. 207). The heaviest rains at Zanzibar Island begin the wet season about mid- April, and last 30 to 40 days; they do not end, however, till early June. Some observers remark that the fall is greatest at low water and during the ebb-tides of the Syzygies. It is, however, rare to have a week of uninterrupted rain, as in eastern India and sometimes in the Brazil. The discharge is exceedingly uncertain. Some years number 85 inches, others 108. During the first eight months of 1857 and the last four months of 1858, we find a total of 120·21 inches. In 1859 it reached 167, doubling the average of Bombay (76·55), and nearly trebling that of Calcutta (56·83). We may compare these figures with those of Europe and the United States. England has 31·97 inches; France, 25·00; Central Germany, 20·00; Hungary, 16·93; Boston, 38·19 (about the same at Beyrut in Syria); Philadelphia, 45·00; and St Louis, Mo., 31·97. Of these 167 inches (1859), 104·25 fell during the Msika Mku. The number of wet days ranges from 100 to 130 per annum. According to the people, rain has diminished of late years; perhaps it is the result of felling cocoas, and of disforesting the land for cloves. In 1857, the Great Msika was preceded by a few days of oppressive heat, which ended (March 24) in a highly electrical storm, like those which usher in the rains of western India, and suddenly the cool S.W. began to blow. For some time we had daily showers, now from the N.E., then from the S.W., with high winds and loud thunderings; the rains, however, did not show in earnest before April 10.