TO RIO JANEIRO. 39 
tude, was 6 15 inches during ten days. The greatest fall in 
twenty-four hours was 1*95 inches. The temperature of the rain 
on several trials varied from 69° to 72°, that of the air being at the 
time 77°. 
The nights were now beautiful until near morning, when it 
generally clouded over, and remained overcast with flying clouds 
until evening. The zodiacal light was once or twice observed, 
but the presence of these clouds for the most part prevented it from 
being seen. 
On the 29th, in latitude 3° 40' N., our observations gave a current 
of ten miles in twenty-four hours, to the north. Until the 3d of 
November we had light winds ; the upper stratum of clouds were 
now seen moving from the east. On the 4th we had a cry of 
breakers from the masthead. We immediately changed our course 
and ran for the appearance, but it proved on nearing it to have been 
one of the many optical illusions seen at sea, from the effect of light 
and shadow. 
On board the Peacock, on the 30th of October, in latitude 1° 30' 
N., longitude 18° W., they witnessed a remarkable appearance, 
resembling the aurora borealis, radiating from the northwest point of 
the horizon in different directions, and extending from southwest 
round by the north to the eastward, at an altitude of from 10° to 
50° ; afterwards reaching to the zenith, and passing over the moon's 
disk, encircling her with a faint halo of twenty degrees in diameter. 
It continued an hour, and although it was bright moonlight, the 
phenomenon was very distinct and beautiful. 
On the 5th, the winds drew to the south-southeast, and we crossed 
the line, as we had intended, in longitude 17° W., which enabled us 
to pass over and examine the supposed locality of the Triton Bank, in 
longitude 17° 46' W., latitude 00° 32' 00" S. The current was 
experienced this day to be setting to the northeast, fifteen miles in 
the last twenty-four hours. This night the sea was extremely 
brilliant, showing in large luminous patches. The light proved to 
be occasioned by a large species of Pyrosoma, some of which were 
ten inches in length, and two inches in diameter. Many other 
phosphorescent animalculse were taken, and some rips that were seen, 
exhibited long lines of brilliant phosphorescent light. Temperature 
of water 76-5°. Our diprJing needle on the equator gave 23° 30'. 
Hourly observations were made for forty-eight hours to ascertain 
the oscillations of the barometer under the equator, (for which see 
