74 
ST. SELENA. 
The large supply of water found in the Island is remarkable, 
there being, apart from the numerous small brackish springs which 
occur on the outskirts and the low lands, no less than 212 fresh 
water springs, yielding daily about 8000 tuns of the purest quality. 
There is, indeed, scarcely a paddock or meadow without its spring 
of the very clearest water. For such a bountiful gift to this Islands 
while the neighbouring one of Ascension is entirely dependent upon 
condensed sea water and collected rain water stored in tanks, I 
think the difference in geological structure accounts. Clouds very 
frequently envelope the high mountainous parts of both these 
Islands, as they do at Madeira and the Canary group, though not to 
so great an extent, and, except on those bright cloudless days 
which sometimes occur, a condensation of moisture is taking place 
night and day. The water thus deposited soaks into the soil, and, 
flowing along the impenetrable upper surface of some substratum of 
thick lava, finds its exit, where the edge of that stratum crops out, in 
the form of a fresh water spring. Ascension appears to differ in this 
respect ; the lava strata do not exist in such broad massive sheets or 
layers, but the whole formation partakes more of a cindery, scori- 
aceous, and porous nature, so that whatever moisture is deposited 
from the clouds on the mountain top penetrates vertically down 
through the Island, and is not, as at St. Helena, arrested in its pro- 
gress by any solid strata. 
The lava beds on the high land, where they have now passed 
into a hard grey or whitish marl, are considerably perforated by 
cylindrical holes, measuring from three-quarters to an inch in 
diameter and two or three inches deep. These holes pass occasion- 
ally into one another, and generally terminate in a conical form. 
Upon close examination their interior surface shows a roughly- 
grooved texture, the furrows running transversely round the sides, 
plainly indicating the marks of some apparatus by which they have 
been bored. In considerable numbers these perforations may be 
seen along the roadside banks, in the neighbourhood of Jolio’s Hole, 
Green Gate, Halley’s Mount, and very generally at the same 
sphere at the time of examination. It is found to hold in solution a considerable quantity 
of neutral salts, principally sulphate of magnesia, and is a mild and effectual cathartic. It 
very nearly resembles the Bristol Hot Wells, but is not so unpleasant to the taste and would 
most probably be found equally useful in the cure of those diseases for which that celebrated 
spring is used.” My failing to meet with this spring would not be altogether conclusive that 
it does not now exist. 
