224 Ascent to the Summit of the Popocatepetl. 
After having for a short time admired this sad and singular sight, 
we returned into the forest; the tent was pitched near the prostrate 
tree where we last year passed so dreadful a night; fires were light- 
ed, and, whilst our mosos were preparing our beds and repast, we 
endeavored to get a little higher up, in order to accustom our lungs 
to breath an air so little congenial to them. 
_ We had returned by six o’clock. Fahrenheit’s thermometer was 
at 50°. The barometer at 19.120 (English inches) ; water boiled 
at 90° of the centigrade thermometer. The humid zone of the hy- 
groscope appeared at 36°, and disappeared at 37° of the interior 
thermometer, whilst the exterior marked 50°. 
Having finished our experiments, we made our preparations for the 
next day. In the night we suffered from the cold. 
On the 29th, at three o’clock in the morning, we started, with a 
fine moonlight, warmly clad, the face and eyes sheltered with green 
spectacles, and a gauze of the same color, which wrapped up the 
whole of our heads. Of my flag I had made a belt. We were seven: 
the three guides already mentioned, M. Gerolt, the Prussian Consul 
General, Mr. Egerton an English artist, Luciano Lopez, his Mexican 
servant, and myself. We each of us had a little bag containing bread 
and a flask of sugar and water. The Indians carried our instruments, 
and some provisions. We walked behind each other, taking care to 
tread in the same steps as the foremost guide, in order to have firmer 
ground. Of course each man carried his iron-shod bamboo. We 
advanced very slowly, and were obliged to rest at about every fifteen 
paces totake breath. The sugar and water were of immense service, 
for, being obliged to keep the mouth open to breathe, the throat be- 
came parched, and a few drops of sugar and water, every five minutes, 
prevented the pain from becoming unbearable. We zig-zagged and 
went sideways: the ascent is so steep, that it would have been dan- 
gerous, and next to impossible to have gone up in a straight line. 
By the time the sun appeared above the horizon, we had reached a 
great height, when we observed a singular phenomenon, but such as 
has already been seen on the banks of the Rhine. The shadow of 
the whole of the volcano was completely visible on the atmosphere. 
It was an immense circle of shade, through which we could see the 
whole country to the horizon, and which rose afterwards far above 
it, terminating by a vapor moving from south to north, the circle 
descending and becoming more and more transparent as the sun 
rose, and in about two or three minutes it was entirely dispersed. 
