174 
GEOGRAPHICAL ERRORS. 
that we were in possession of microscopes, telescopes, and 
electrical apparatus. 
I could not begin a regular course of astronomical obser- 
rations before the 28th of July, though it was highly im- 
portant for me to know the longitude given by Berthoud’s 
time-keeper ; but it happened, that in a country where the 
sky is constantly clear and serene, no stars appeared for 
several nights. The whole series of the observations I made 
in 1799 and 1800 give for their results, that the latitude of 
the great square at Cumana is 10° 27' 52", and its longitude 
66° 30' 2". This longitude is founded on the difference of 
time, on lunar distances, on the eclipse of the sun (on the 
28th of October, 1799), and on ten immersions of Jupiter’s 
satellites, compared with observations made in Europe. The 
oldest chart we have of the continent, that of Don Diego 
Bibeiro, geographer to the emperor Charles the Fifth 
places Cumana in latitude 9° 30 ; which differs fifty-eight 
minutes from the real latitude, and half a degree from that 
marked by Jefferies in his American Pilot) published in 
1794. During three centuries the whole of the coast of 
Terra Firma has been laid down too far to the south : this 
has been owing to the current near the island of Trinidad 
which sets toward the north, and mariners are led by their 
dead-reckoning to think themselves farther south than they 
really are. J 
On the 17th of August a halo round the moon fixed the 
attention of the inhabitants of Cumana, who considered it 
as the presage of some violent earthquake; for, according 
to popular notions, all extraordinary phenomena are im- 
mediately connected with each other. Coloured circles 
around the moon are much more rare in northern coun- 
tries, than in Provence, Italy, and Spain. They are seen 
particularly (and this fact is singular enough)' when the 
sky is clear, and the weather seems to be most fair and 
settled. Under the torrid zone beautiful prismatic colours 
appear almost every night, and even at the time of the 
greatest droughts ; often in the space of a few minutes they 
disappear several times, because, doubtless, the superior 
currents change the state of the floating vapours, by which 
the light is refracted. I sometimes even observed, between 
the fifteenth degree of latitude and the equator, small halos 
