170 METEOROLOGICAL AND 
masses, over a pale brassncoloured ground; as the gale 
breaks, the clouds assume a darker colour. The sky in- 
variably assumes this pale brass-colour before the gale 
comes on. An old pilot, who had been upon this coast 
for thirty years, first mentioned this to me : he said, when- 
ever he saw the sky have that brassy-like appearance, and 
those double-headed clouds^ he was sure that a westerly gale 
was coming on. What he meant by his double-headed 
clouds, were those rounded masses I mentioned above: 
they are of different shades ; the light-coloured are highest, 
and they shew out from under the darker ones, giving just 
that appearance which is best expressed by double-headed. 
I have been thus particular about the weather here, to 
shew the very great advantage which may be derived from 
the study of the barometer ; for had I not been prepared 
before the gale came on, I most certainly should have lost 
my masts, and most likely the ship and our hves ; for on 
our arrival at St Helena, we found our foremast so rotten, 
that it was a wonder, after all our precaution, how it stood 
during the gale, 
4. On Under-Currents, 
I have only a very few remarks to make respecting 
the under-currents. That there are under-currents in 
the ocean, I ascertained in the following manner. After 
having moored the boat in the usual manner, I lower- 
ed a very large white flag down a few fathoms below 
the surface, and was surprised to see it carried out by a 
current in an opposite direction to the current which was 
running on the surface. In Lat, ST 38' S. Long. 13° 45' W. 
the current on the surface set E. by S. 7 miles ; at 10 fa- 
