886 
EXCESSIVE HEAT. 
compared them in my journal to the paterlestein of Fich 
telberg, in Franconia, which is also a diabase, but so fusi- 
ble, that p'ass buttons are made of it, which are employed 
in the slave-trade on the coast of Guinea. I believed at 
first, according to the analogy of the phenomena furnished 
by the mountains of Franconia, that the presence of these 
hornblende masses with crystals of common (uncompact) 
feldspar indicated the proximity of transition rocks ; but 
in the high valley of Caracas, near Antimano, balls of the 
same diabase fill a vein crossing the mica-slate. On the 
western declivity of the hill of Cabo Blanco, the gneiss is 
covered with a formation of sandstone, or conglomerate, 
extremely recent. This sandstone combines angular frag- 
ments of gneiss, quartz, and chlorite, magnetieal sand, 
madrepores, and petrified bivalve shells. Is this formation 
of the same date as that of Punta Araya and Cumana ? 
Scarcely any part of the coast has so burning a climate 
as the environs of Cabo Blanco. We suffered much from 
the heat, augmented by the reverberation of a barren and 
dusty soil ; but without feeling any bad consequences from 
the effects of insolation. The powerful action of the sun 
on the cerebral functions is extremely dreaded at La Guayra, 
especially at the period when the yellow fever begins to 
be felt. Being one day on the terrace of the house, observ- 
ing at noon the difference of the thermometer in the sun 
and in the shade, a man approached me holding in his hand 
a potion, which he conjured me to swallow. He was a phy- 
sician, who from his window, had observed me bareheaded, 
and exposed to the rays of the sun. He assured me, that, 
being a native of a very northern climate, I should infalli- 
bly, after the imprudence I had committed, be attacked with 
the yellow fever that very evening, if I refused to take the 
remedy against it. I was not alarmed by this prediction, 
however serious, believing myself to have been long ac- 
climated; but I could not resist yielding to entreaties, 
prompted by such benevolent feelings. I swallowed the 
dose ; and tlia physician doubtless counted me among the 
number of those he had saved. 
The road leading from tho port to Caracas (the capi- 
ta] of a government of near 900,000 inhabitants) resem- 
bles, as I have already observed, the passage over the Alps, 
