290 REACTION OP THE INTERIOR OF THE EARTH 



from the Atlantic to the Pacific, an important and, for 

 that reason, a much contested geological phenomenon. 

 By tracing upwards the great stream of lava which had 

 flowed from the new volcano, I succeeded in pene- 

 trating deep into the interior of the crater, and iu 

 setting up my instruments there. , The theatre in which 

 this great natural event took place was a wide and 

 previously long-tranquil plain in the former province of 

 Michuacan, more than 120 geographical miles from any 

 other volcano ; the time was the night of the 28th to the 

 29th of September 1759 ; and for two full months previ- 

 ously, uninterrupted subterranean noises had been heard. 

 Unlike the wonderful "bramidos" of Gruanaxuato in 1784, 

 which I have described elsewhere ( 429 ), these noises were 

 accompanied, as is more usually the case, by earthquake 

 shocks, which phenomenon was altogether absent in the 

 neighbourhood of Gruanaxuato in 1784. The upheaval 

 of the new volcano, at 3 A.M. in the morning of the 

 29th September, was announced on the preceding day 

 by a phenomenon which in other eruptions usually 

 marks, not their beginning, but their end. On the 

 spot where the volcano now stands there was formerly 

 a thick growth of Gruava trees (Psidium pyriferum\ 

 of the fruit of which the natives are particularly fond. 

 Labourers from the sugar-plantations of the Hacienda 

 de San Pedro Jorullo, belonging to the wealthy pro- 

 prietor Don Andres Pimentel, who was then living in 

 Mexico, had gone out to gather guavas. When they 

 returned to the hacienda, it was remarked, with astonish- 

 ment, that their wide straw hats were covered with 

 volcanic ashes. From this it would appear that, in 

 what is now called the Malpais, probably at the foot of 



