p. Waits — Popocatepetl Again in Activity. 85 



last lava eruption of the volcano fell back into the 

 chimney and which during the two centuries of little 

 activity on the part of the volcano lay buried under the 

 debris of the crater walls and later on under a lagoon. 

 The recent activity of the volcanic focus has pressed the 

 plug slowly upward, and if, as seems probable, this 

 activity should continue to increase, we may perhaps be 

 able to observe the formation of a Pelee-needle within the 

 crater of the volcano. But it is more probable that the 

 course of events will be similar to those which we have 

 been able to study on the volcano of Colima, where we 

 have observed that during the course of nearly a century 

 the formerly deep crater has been slowly filled up to the 

 rim with block-lava. 



We had the opportunity to observe that all the steam 

 explosions which occurred in separate puffs during our 

 stay on the crater, had their origin between the plug and 

 the crater walls, while the plug itself showed no develop- 

 ment of steam. Later visitors to the volcano, among 

 whom was a gentleman who had accompanied me on my 

 excursion, believed they were able to observe, on the first 

 of November, that the plug meanwhile had been raised 

 still farther, and that isolated emanations of steam now 

 occurred also within its mass, and, judging from the 

 yellow color, emanations of sulphur also. 



From time to time the steam explosions (with the 

 steam there is always mixed some sulphur dioxide (SO2) ) 

 seem to throw up sand and ashes ; we have been able to 

 observe fresh accumulations of this material on the 

 lowest portion of the crater rim and in these deposits 

 the traces of larger stones also, which cannot very well 

 be called bombs, because they were not of freshly molten 

 material. 



The steam explosions are connected with very strong, 

 thunder-like noise, which can be very well heard as far as 

 Tlamacas at least. Strong eruptions throw the steam 

 out above the crater rim in thick clouds, which on account 

 of their whirling movement take the form of cauliflower 

 clouds.. The explosion which we observed from Tlamacas 

 on the 12th of October at 7 a. m., rose at least 500 m. 

 above the highest point. We could not observe any kind 

 of earthquake during the eruption, even in cases of strong 

 explosions, and standing at the crater rim itself. Smaller 

 eruptions of steam generally disperse within the wide 

 crater, the longitudinal axis of which is, according to the 



