Chap. III. ELECTRICAL PHENOMENA. 457 
From the watering-place, we first proceeded to a deso- 
late plateau, covered with grey bushes and scanty grass, 
where we saw large herds of antelopes. In a few hours 
we reached a level tract, upon the bare clay soil of which 
grew, here and there, an Opuntia arborescens. In the 
distance rose the Limpia Mountains, to which our road 
lay. At their foot we observed some columns of smoke- 
Indian signals, as we ascertained some days later. During 
the journey the sky was overcast with dark clouds, which, 
with a sultry air, seemed to indicate the approach of 
a thunderstorm. Some large drops of rain fell : a 
violent gale filled the air with such clouds of dust 
that we were almost stifled, and our caravan was quite 
darkened. Later, when night came on, our clothes and 
the harness emitted electric sparks when stirred : every 
lash of the whip on the animals' backs was a small streak of 
fire. I have often witnessed similar electrical phenomena 
in the interior of North America, and have before spoken 
of them ; but have never seen them exhibited in so striking 
a manner as on this day (February 24th) on the plain of 
the eastern foot of the Limpia Mountains : sparks from 
my fingers were at times quite perceptible when I touched 
any part of my clothes. I may here observe that, coin- 
ciding with these electrical phenomena, I repeatedly felt a 
sudden rheumatic affection, which all at once paralyzed, 
temporarily, my left leg, and gave me a violent headache. 
The former attack, happily, never lasted above one or two 
hours. 
We continued our route till about two o'clock in the 
morning, during which time the warm air was succeeded 
by an icy north wind, accompanied by a snow-storm, 
which obliged us to halt for twenty-four hours. Our 
animals had all this time no water, but they appeared 
