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of Edinburgh, Session 1869 - 70 . 
vertically beneath the sun’s rays, and thus moving up and down 
the face of the land within the tropics, gives the wet and dry, the 
cold and hot, seasons of the year in this region. On the coast 
the seasons are sharply defined : the continental and the oceanic 
monsoons divide the year between either a single or a double 
wet and dry season ; but in the high interior plateau in which the 
lakes are situated, the winds are drawn into the pendulating area 
of low pressure from the ocean, nearly throughout the year, and it 
is only when extreme limits of the tropical zone come directly 
under the sun, that a higher barometric pressure, an outflow of the 
winds, and a consequent dry period, is experienced here. 
In the coastland under the equator, the country explored by the 
German traveller Brenner, the mean temperature of the year is 
85 0, 1 (mean of three daily observations), the highest observed tem- 
perature (of 92 0, 8) having occurred in January, and the lowest 
(73 0, 4) in May. The rainy season here sets in with the south-east 
monsoon in April, and lasts till the end of June. The second 
rainy season, which we shall notice, taking place farther south in 
September and October, is almost lost at the equator. The north- 
east monsoon brings a cloudless sky of clear blue, and begins to 
blow here in November, lasting till March, and in this season rain 
is never thought of. 
At Zanzibar Island, six degrees south of the equator, the mean 
temperature of the year is nearly 80° Fahr., rising in January to 
an average of 83°, falling in July to 77°; and it has a double rainy 
season, a stronger in March, April, and May, when the column of low 
pressure has passed this latitude in moving northward ; and again 
in a weaker in September and October, when the low pressure 
passes in its southward course, at which times the monsoon winds 
change from the north-east, blowing out of Asia towards South 
Africa, to the south-west, blowing from Africa towards the Asiatic 
continent. In the low countries, beneath the edge of the plateau, 
about Zungomero, Burton tells us that the rain is constant, except 
for a single fortnight in the month of January; at most times the 
sun shines through a vale of mist with a sickly blaze and a blister- 
ing heat, and the overcharge of electricity is evinced by frequent 
and violent thunderstorms, so that the climate of Zanzibar is 
equally ruled by these two great land masses. On the Mozambique 
