The barometer, so near the equator, is almost uniformly sluggish and quiescent. Its range diurnal and annual is here at a min. It seldom, except under varying pressure of storms or tornadoes, rises or falls above or below 30 inches at sea level, and a few tenths represent the max. variation. It must be observed, however, on both coasts of Africa, within 6°-7° of the Line, this instrument requires especial study for nautical purposes. Here it is an imperfect indicator, because, affected from great distances, it rises without fine weather and it falls without foul. At Zanzibar the case of a whaling captain is quoted for wasting in vain precautions nearly two months. Moreover, sufficient observations have not yet been accumulated in the southern hemisphere. Where there is so little expansion in the mercurial column the convexity and concavity of the column-head must be carefully examined with a magnifying-glass, and by a reflecting instrument the smallest change could be correctly measured. The trembling of the aneroid needle, sometimes ranging through a whole inch during the gusts of the highly electrical tornado, also calls for observation. The sympiesometer is held to be even more sensitive than the mercurial barometer, especially before storms, and ignorance of its peculiarity has often ‘frightened a reef in’ at unseasonable times. The same was found to be the case, in high latitudes, by Lieut. Robertson, R.N., when sailing under Captain Ross (1818), between N. lat. 51° 39′ and 76° 50′. Observations with the altitude and azimuth determined the variation of the needle in 1857 to be between 9°-10° (W.). If this be correct, it is gradually easting. In 1823 Captain Owen found it to be 11° 7′ (W.).[39] So, upon the opposite coast, the variation laid down in our charts of 1846 as 20° (W.) has gradually declined to between 18° 30′ and 19° (W.). Of exceptional meteoric phenomena I can speak only from hearsay, no written records existing upon the island. A single earthquake is remembered. In the early rains of 1846, at about 4 P.M., a shock, accompanied by a loud rumbling sound, ran along the city sea-front, splitting the Sayyid’s palace, the adjacent mosque, and the side-walls of the British Consulate, in. a direction perpendicular to the town. It was probably the result of igneous disturbance below the coralline, and it tends to prove that the island was originally an atoll: some, however, have explained it by a land-slip. Three meteors are known since 1843. In December of that year a ball of fire was visible from windows facing the north; it disappeared without a report. The most remarkable was a bolis, which, about 6 P.M. on October 25, 1855, took a N.W. by W. path, burned during ten or eleven minutes, and frightened the superstitious burghers into fits. Water-spouts commonly appear during the month of April, and in the direction of the mainland: the people disperse them by firing guns.