ST HELENA. 



INTRODUCTORY NOTES. 



St Helena is situated about 700 miles south of Ascension, and lies in lat. 15° 55' S., and 

 long. 5° 42' W., or about 1100 miles from the coast of Africa, and 1800 miles from the 

 nearest part of America. It is about ten miles long by eight miles broad, and is wholly 

 volcanic, its surface being very rugged, irregular, and mountainous ; and its greatest 

 height is 2700 feet above sea-level. Nearly the whole of the coast-line consists of a wall 

 of rock, rising in places to a height of 2000 feet, and broken only by narrow ravines that 

 radiate from the centre of the island and increase in size and depth towards the coast. 

 The estimated area of the island is 28,000 acres, whereof two-thirds at least are now waste. 



The climate is described as one of the most equable and enjoyable in the world, being 

 free from thunderstorms and hurricanes. The mean temperature for five years (1841 to 

 1845 inclusive) at Longwood, an altitude of 1764 feet, was 61 '4° Fahr. ; the lowest during 

 this period was 52°, and the highest 77'6°; and the annual rainfall at the same place is 

 about 44 iuches. Descending towards the coast there is an increase of temperature with 

 a smaller rainfall, and in Jamestown itself the heat is oppressive in summer. In the 

 higher parts of the island there is a considerably larger rainfall than at Longwood, with, 

 of course, a lower temperature. 



Melliss 1 distinguishes three climatic zones characterised by different plants. The first 

 is a rocky belt extending all round the coast and for a mile inland ; it possesses a hot 

 scorching atmosphere, 10° Fahr. higher in temperature than the mountain-top, and ranges 

 in altitude from the sea-level up to 2272 feet. Except in the sheltered and watered 

 ravines it is very barren. 



The second or middle zone lies inside of the first, extending for three-quarters of a 

 mile inland, and varying in altitude from 400 to 2000 feet. It is less rocky than the 

 outer zone, its temperature is 5° Fahr. lower, and its vegetation is scanty. 



The third zone consists of the centre of the island, an area about four miles long and 

 two and a quarter miles wide, varying from 1200 feet to the highest summits. It has a 

 deep soil, and is entirely covered with vegetation. 



Vegetation — Historical Sketch. 2 

 St. Helena was discovered by a Portuguese, Jean de Noya, in 1501, on the 18th 

 of August, St. Helena's day, hence the name the island bears. At that date it was 



1 St Helena, p. 231. 



2 For many of the facts in this sketch we are indebted to Sir Joseph Hooker's Lecture on Insular Floras, 

 read before the British Association for the Advancement of Science in 1866, and printed in the Gardeners? 

 Chronicle for 1867. 



(bot. CHALL. EXP. — PART n. — 1884.) B 7 



