ilii
4 V O Y A G E TO T H E
C H A P , of this gigantic cone. The sun set behind i t ; and as his beams
Ju n e ,
1825.
withdrew, the mountain was thrown forward, until it appeared not
half its real distance. Then followed a succession of tints, from the
glomng colours of a tropical sky, to the sombre purple of the deepest
valleys; varying in intensity with every intermediate range, until a
landscape was produced, which, for beauty of outline, and brilliancy
of colour, is rarely surpassed; and we acknowledged ourselves amply
repaid for our days of suspense. Night soon closed upon the view;
and, directing our compass to a well-known headland, we took
our last look at the island, which was the only one of the Canary
groupewe had seen: not on account of our distance from them, but
owing to that mass of clouds which “ navigators behold incessantly
piled over this Archipelago.” The breeze was fair, and we rolled on,
from day to day, with our awnings spread; passing rapidly over the
ground with a fresh trade-wind, and daily increasing the heat and
humidity of our atmosphere : amused, occasionally by day, with shoals
of flying-fish starting from our path, followed by their rapacious pursuers
; and by night, with the phosphoric flashing of the sea, and the
gradual rising of constellations not visible in our own latitude.
Toward the termination of the trade, the wind veered gradually
to the eastward, and became fresh, until noon of the 15th, when it
suddenly ceased, and the sea, foaming like breakers, beneath a black
thunder-cloud, warned us to take in our lighter sails. We were presently
taken aback with a violent gust of wind from the southward,
and from that time lost the north-east trade. As we approached its
limit, the atmosphere gradually became more charged with humidity,
and the sky thickened with dark clouds, which, latterly, moved heavily
in all directions, pouring down torrents of rain.
On the I6th, the sun was eclipsed; and we made many observations
to determine the moment of conjunction. In doing this, my attention
was arrested by a very unusual appearance. It consisted of
a luminous haze about the moon, as if the light had been transmitted
through an intervening atmosphere. I made a sketch of it very soon
afterwards*, of which I was very glad, as a similar phenomenon, I found,
* See AppenclLx.
had been observed by M. Dollond in another eclipse; and as the sub- C H A P
ject has since received much interest from the circumstance of Aldebaran,
June ,
1825.
and .Tupiter and his satellites, having been seen projected uiron
the disc of the moon. About the time of the greatest obscuration,
Leslie’s photometer stood at 27°, exactly half what it afterwards
showed. Between the intervals of observation, we amused ourselves
with making experiments with a burning glass upon differently
coloured cloths, in imitation of those recorded in the Correspondence
of Baron de Zach, and which will convey to the general reader a more
intelligible idea of the decrease of intensity in the sun’s rays at the
time of the greatest obscuration, than the observations with the
photometer, as well as of the readiness with which some colours
ignite in comparison with others: for instance.
Black
burned in s ta n tly ;
Blue
required 3",7»
Scarlet,
1 5 '',7:
P e a -G re en
would n o t ignite.
After the eclipse, and when the sun was shining bright,
Black
b urned instantly;
Blue,
in s ta n tly ;
Scarlet,
2" ;
P e a -G re en , Yellow,
7", 8 ; 4",3.
The results are the mean of several observations ; and the intervals, the
time between the rays being brought to a focus on the cloth, and its
ignition.
After losing the trade-wind, we went through the usual ordeal of
baffling winds and calms, with oppressively hot moist weather, and
heavy rains ; and then, on the 19th, in latitude 5° SO' N., got the
south-east trade, with which we pursued our course towards the equator,
and crossed it on the 24th, in longitude 30° 2' West, much further
from the meridian of Greenwich than choice would have dictated.
Some anxiety was in consequence felt lest the current, which here ran
to the westward at the rate of thirty miles a day, should sweep the
ship so far to leeward, as to prevent her weathering Cape St. Eoque,
the north-eastern promontory of the Brazil coast, and thus materially
protract the passage, as it would be necessary to return to the variable
winds about the equator to regain the easting, in consequence of the