2 54 
Coris co. 
Corisco, which the natives know as Mange : it 
was called, says Barbot, “ ‘ I Ilia do Corisco,’ from 
the Portuguese, because of the violent horrid 
lightnings, and claps of thunder, the first dis¬ 
coverers there saw and heard there at the time of 
their discovery.” There is still something to be 
done in investigating the cause of these electrical 
discharges. Why should lofty Fernando Po and 
low-lying Corisco suffer so much, when Zanzibar 
Island, similarly situated, suffers so rarely ? Again, 
why is Damascus generally free from thunder¬ 
storms when Brazilian Sao Paul, whose site is of 
the same altitude and otherwise so like, can hardly 
keep the lightning out of doors ? The immu¬ 
nity of Zanzibar Island can hardly be explained 
by the popular theory ; neither it nor Fernando 
Po, which suffers greatly from thunder-storms, lies 
near the embouchure of a great river, where salt 
and fresh water may disturb electrical equilibrium. 
I shall say more upon this point when in the 
Congo Regions (chap. xii.). 
The position of Great Corisco (north latitude 
o° 55' o") is at the mouth of a well-wooded bay, 
which Barbot (iv. 9) calls Bay of Angra, i.e. 
Bight of Bight. He terms the southern or 
Munda stream Rio de Angrta, or Angex, whilst 
the equally important Muni (Danger) becomes 
only “a little river” without name. The modern 
charts prefer Corisco Bay. It measures some 
