CHAPTER IV. 1. ELEVATION OF THE EARTH ABOVE THE LEVEL OF THE OCEAN.- Elevation. Gambia site. THE elevation of a country or place above the level of the sea is of very great importance in a sanitary point of view; the generally acknowledged maxim-the higher we ascend the more healthy we become—is nowhere to be regarded as of greater practical utility than in the tropics. In Western Africa we find that the poorer classes of inhabitants, who occupy mud-huts and sleep on mats spread on the bare mud floor, present a greater mortality than even those who occupy the same species of huts, but sleep on sofas one or two feet above the ground. The frame houses, raised about two feet above the ground by stone pillars, allowing a current of air to circulate under the flooring, are the most healthy of the houses of this description in the tropics, and their inhabitants present less annual mortality than those who inhabit mud-huts. The site of the British colony on the banks of the River Gambia is so low that it is scarcely two feet above the level of the sea; in some places it is below the sea-level; and Bathurst, every year, is subject, at any very high seas, between July and September, to be inundated, as was the case in 1847 and 1851. Lately Col. D'Arcy, the governer, with his superintendent of police, has worked hard to remedy this state of things; and a barricade has been made to prevent these unpleasant results. In the immediate neighbourhood of St Mary's, and at Combo, there are extensive plains of offensive and pestilential swamps, which, during the rains and the blowing of the N.W. and S.W. monsoon, add greatly to the unhealthiness of the colony. For the sum of L.7000, says Major Clerk, R.N., this swamp, covering nearly 1000 acres of land, can be most effectually drained; but the exchequer of the colony being in a very impoverished state, there is no hope this recommendation will be carried out. Bacchou, or Cape St Mary's, is situated on a small Bacchou, or rising ground facing the sea; it is the most healthy spot around Mary's. St Mary's, and has been used as an invalid station from Bathurst. Cape St Island. M'Carthy's Island, another station situated about 250 miles M'Carthy's in the interior, is about 5 miles in length and 1 in breadth. During the rains it forms an extensive plain of muddy swamp, with a pool of water dividing it almost in two, and emptying itself into the river. It presents no high ground, and when there happens to be a severe rainy season, the island is almost flooded with water. There are large ditches and trenches made at various parts of Georgetown to carry away aqueous accumulations, but the number is too small for the requirements of the place. Towards the end, and in the beginning of the rains, these pools are converted into muddy swamps, exhaling a most deadly vapour. M'Carthy's Island is exposed to whatever influence of wind it might be subject to, whether mephetic or hygienic, towards the S.W., W., N.W., N., and N.E. At the east and south it is imperfectly sheltered by a low range of hills in the mainland, which is nearly 200 feet high. The general inclination is from N.E. to N.W. The barracks of M'Carthy's, hygienically, should have been built on the range of hills on the mainland, which is known as Fa-to-to hill, situated on the east of the island, on the Nyanney ground. Their elevation is sufficient to moderate the heat, Albreda. Sierra Leone site. which is so intense in the hot season among the swamps of the lowland. The general, as well as local inclination of the colony at Bathurst, including Combo and Bacchou, is towards the swampy banks of the river, and consequently N.E. to N.W. There are no elevated spots around these stations, no mountain or hills, but one flat plain, which is exceedingly swampy during the rains. A few miles from Bathurst, along the river, is the town of Albreda, formerly belonging to the French, but exchanged for Potendie with the British Government. It is built on the declivity of a small range of hills, and forms a more eligible and important station for the principal seat of government than St Mary's or even the Cape. If the summit of the hill be occupied, it will not be very inferior to Cape St Mary's for healthiness, and very far superior to Bathurst or St Mary's; but in a commercial and political point of view it will be superior to any other point on the River Gambia. At present it is the seat of an extensive trade with the natives, but is neither a military nor a colonial station. An extensive range of bold lofty mountains, running from W.S.W. towards E., and then shaping itself to the south, forms the peninsula of Sierra Leone. They are, I believe, of a volcanic origin, although many have thought that they must have been produced by a huge process of denudation. The highest of Sugar-Loaf. these ranges is Regent Mountain or Sugar-Loaf, about 3000 feet above the level of the sea, and commanding a most extensive view. Uninfluenced by any local peculiarities, it is subject to all the climatorial changes in the weather, and, from its height, receives the breeze in the very same state from whatever position it may proceed. From Sugar-Loaf the mountain runs towards E.S.E. until it becomes partially lost a little way beyond Hastings, or merges into the Waterloo range, the highest peak of which is known as Mount Horton, which terminates abruptly between Kent and York, facing the Atlantic. Another range in front, and to the south and east of the former, commencing from Signal Hill, where it is almost 400 or 500 feet above the level of the sea, ascends gradually through Wilberforce to Leicester, where it abruptly forms itself into a cone, from 1500 to 2000 feet above the level of the sea. From hence the range occupies the front and rear of Gloucester, meeting at a juncture between Kissy and Bathurst, and terminating gradually from Wellington to Allen Town. and declivi The general declivity of Sierra Leone is therefore towards Local aspect the east and south-east, but there are great differences in its ties, local declivities. The whole of the towns and villages of Sierra Leone are either partially or wholly built on elevated spots, but the numerical difference in their healthiness depends, I am of opinion, on their local aspect. In a sanitary point of view, the spot now occupied by the Freetown. city of Freetown is the most unhappy that could have been selected for the capital and entrepôt of trade. It is covered towards the south and south-east, south-west and west, by high and lofty mountains; its aspect or declivity is towards the north and east, facing the mainland, and exposed but very impartially to the north-west or the ocean. It is built in the plain at the foot of the lesser chain of mountains already described, where it makes an angle between Signal Hill and Kissy Range, and is therefore screened from all breezes arising from south-east to west. At the centre of the town is an abrupt hill, about 400 feet high, possessing a table-land at its summit, which is occupied as a military station. The town around is low, except in front, where there is a gradual ascent from the river to this elevation, which is called "Tower Hill." It is a well-known fact, that by a proper exposure of the soil Effects of to the action of the sun a most beneficial result is obtained. "A hill inclined 45° to the south, when the sun is elevated 45°, receives solar rays perpendicularly, whilst upon a plain the same rays strike the soil under an angle of 45°, that is, with one quarter less of force; and a hill inclined 45° to the north will be struck by the solar rays in a horizontal direction, which makes them glide along its surface." Again, local aspect has a most powerful effect in altering the effects of the prevailing sun's rays. December solstice. winds in a country; and these two results, viz., the action of the sun on the soil, and the alteration of the effects of the prevailing winds by local aspect or declivity, but principally the latter, must be regarded as the grand keystone to an explanation of the unhealthiness of the city of Freetown in Sierra Leone (and not, as has been most wrongly stated in books, the colony of Sierra Leone). During the December solstice the sun is about 32° south of Freetown, and its benign influence is consequently lost early in the day, through the interruption of Leicester Mountain and afterwards Sugar-Loaf; that is, towards evening evaporation decreases and condensation begins to take place earlier, through the loss of the direct rays of the sun. We know also that malaria is generated and concentrated on the surface of the earth, or just above it after sunset, when the heated and consequently rarefied air becomes cooled down; any influence, therefore, which deprives a place of the full action of the sun does to a certain extent predispose it to disease. Fortunately, however, at the December solstice there are other climatic influences which moderate the injurious effect that might have been proJune solstice. duced. In the June solstice the sun sets about 15° north of Freetown, but its rise is interrupted by the position of the lesser range of hills, and the town receives the sun's rays only in a slanting direction. Tower Hill interrupts in some measure, secondarily, the due action of the sun in every part of Freetown; its position in the very centre of the town has a direct influence, at whatever position in the compass the sun rises or sets. Monsoon. Towards the end of the October or north-east monsoon, namely, at the beginning of April, the wind shifts from N. and N.E. to S.W. and W., but occasionally blowing from E. and N.E. At this time the rain gradually begins to fall; the dried up dead vegetable matter receives moisture and begins to putrefy, and consequently forms the source of unhealthy exhalations. The wind from E. and N.E. blows from the Continent through an extensive track of these unhealthy emanations,—through |