METEOROLOGY. 
387 
Sabine, E.A., R.R.S., and subsequently published. Longwood is 
itself a bleak, cold, exposed situation; and the complaints of 
Napoleon’s staff against it as such were not without some reason. 
On this account it is perhaps not the most favourable spot for 
recording observations characteristic of the meteorology of the Island ; 
still they may be taken as affording a tolerably correct record. 
The building erected for these observations stands in. Lat. 
15° 56' 41'2" S., Long. 5° 40' 31-5'' W., at an altitude of 1764 feet 
above the sea, and about two and a half miles from it. The mean 
temperature of five years was 61 - 4°; the lowest being 52°, on 
the 5th September, 1845, and the highest 77 - 6°, on the 3rd March, 
1842 ; the mean taking place at nearly equal intervals between — viz., 
early in June and about the middle of December. The mean height 
of the thermometer in the different months ranged from 57‘07° in 
September to 66 -24° in March, making an average difference of only 
9 17° between the hottest and coldest months. The extreme range 
of thermometer being 25'6°, and the mean diurnal range 5-6°.* 
Over many miles of ocean blows the South-east Trade, as pure a 
wind as is found on the face of the earth, sometimes accompanied by 
rain and sea-fog, and sometimes sweeping across the plains of Long- 
wood and down the ravines with force enough to uproot trees and un- 
roof houses, while many a sheltered glade in other parts of the Island 
experiences little of its fury. These strong Trades, with a force of 
1-72 lbs., f are the nearest approach to a storm that ever occurs at St. 
Helena. They are generally strongest in the months of September 
and October ; and it is remarkable that at times while they blow 
with fury round the coast, even driving ships to sea from the snug 
anchorage on the leeward side, a perfect calm exists on the moun- 
tain ridge at Diana’s Peak, only 2697 feet higher up. 
Clouds often hang over the whole Island, high above the land, lor 
several days together, giving rise to the local expression, “ a covered 
day.” They seem spread out over the land like a huge umbrella, 
as a protection to young verdure from the fierce rays ol the sun. 
Rainy seasons happen twice in the year — in summer and winter ; 
the summer rains are heavy, the latter light and misty, but continuous. 
At each period heavy floods are likely to occur, doing considerable 
damage to gardens and roads, which latter are necessarily very steep. 
* Appendix, pp. 396, 397. t Appendix, p. 398. 
c c 2 
