350 
EADIANCE OE THE ST AES. 
their feet,* as it is heard by us in the region of the clouds. 
Confidence easily springs up in the human breast : on the 
coasts of Peru we become accustomed to the undulations 
Df the ground, as the sailor becomes accustomed to the 
tossing of the ship, caused by the motion of the waves. 
The reddish vapour which at Cumana had spread a mist 
over the horizon a little before sunset, disappeared after 
the 7th of November. The atmosphere resumed its former 
purity, and the firmament appeared, at the zenith, of that 
deep" blue tint peculiar to climates where heat, light, and 
a great equality of electric charge seem all to promote the 
most perfect dissolution of water in the air. I observed, on 
the night of the 7th, the immersion of the second satellite 
of Jupiter. The belts of the planet were more distinct than 
I had ever seen them before. 
I passed a part of tlio night in comparing the intensity 
of the light emitted by the beautiful stars which shine in the 
southern sky. I pursued this task carefully in both hemi- 
spheres, at sea, and during my abode at Lima, at Guayaquil, 
and at Mexico. Nearly half a century has now elapsed 
since La Caillc examined that region of the sky which is 
invisible in Europe. The stars near the south pole are 
usually observed with so little perseverance, and attention, 
that the greatest changes may take place in the intensity 
of t heir light and their own motion, without astronomers 
having the slightest knowledge of them. I think I have 
remarked changes of this kind in the constellation of the 
Crane and in that of the Ship. I compared, at first with 
the naked eye, the stars which arc not very distant from 
each other, for the purpose of classing them according to 
the method pointed out by Herschel, in a paper read to 
the Royal Society of London in 1790. I afterwards em- 
ployed diaphragms diminishing the aperture of the teles- 
cope, and coloured and colourless glasses placed before the 
oye-glass. I moreover made use of an instrument of re- 
flexion calculated to bring simultaneously two stars into the 
field of the telescope, after having equalized their light by 
receivirg it with more or fewer rays at pleasure, reflected 
by the "silvered part of the mirror. I admit that these 
photometric processes are not very precise : but I believe 
* Loa bramidos de Guanazuato. 
