106 FieLp CoLumMBian MusrEuM—GEo.ocy, VOL. I. 
son brothers, residents of Miraflores, who had gained the summit by 
a route somewhat different from that usually taken. As this infor- 
mation was, however, of a hearsay character, I was unable to give it 
much credence. 
The ascent of Ixtaccihuatl seems, therefore, pretty generally to 
have foiled those who have attempted it. 
While the difficulties are without doubt great, my own observa-: 
tions lead me to conclude that the failures have been due to lack of 
suitable preparation rather than to the absolute impracticability of the 
undertaking. Two parties have failed because their ascent was made 
in April, when severe snow storms descend upon the mountain. 
Hence, one of the winter months, such as January or February, 
should be chosen. Other parties have failed for lack of suitable 
means to cross the crevasses and treacherous ice surfaces. To over- 
come these obstacles, rope ladders, foot swaths and guide ropes 
should be taken, and all the precautions found necessary in Alpine 
climbing be observed. The party should also be provisioned so as to 
be able to spend a week if necessary on the slope of the mountain. 
Thus prepared, if the course of ascent is checked in one direction it 
can be undertaken in another, and by three or four trials the possi- 
bility or otherwise of reaching the summit can be demonstrated. The 
difficulties of the climb are, of course, greatly increased by the severe 
cold and rarefaction of the air, but that these alone would not prevent 
reaching the summit is shown by the many successful ascents of 
Popocatepetl. 
It is desirable that further ascents of the mountain should be 
made in order to definitely determine its height. As the follow- 
ing table will show, there exist at present great discrepancies in the ~ 
values obtained for this, and the differences are the more tantaliz- 
ing from the fact that the probabilities of accuracy seem about equal 
for the two sets of values: According to Humboldt and Lenk the 
altitude of the mountain is less than 16,000 feet; according to Sonn- 
tag and Heilprin it is fully 17,000. The measurements of both Hum- 
boldt and Sonntag were trigonometric, and their work in other respects 
is of a character to warrant the highest confidence. Yet, though 
their determinations of the altitude of Popocatepetl differ only about 
70 feet, those of Ixtaccihuatl have a variance of nearly 1,400 feet. 
Heilprin warmly supports Sonntag’s value, both on account of his 
own barometric results and from the fact that, to the eye, ashe states, 
Ixtaccihuatl appears as high as Popocatepetl, many persons even 
affirming that the former is the more elevated. 
On the other hand, Lenk is positive that Sonntag’s determination 
is incorrect. Hestates that from the point on Ixtaccihuatl reached 
wan 
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