258 M. Boussingaulfs [Oct. 



favourable ; the sun was hot enough to inconvenience us. 

 About 3 o'clock we observed some clouds forming beneath 

 in the plain ; thunder was soon heard below our station ; 

 the sound was not intense, but it was prolonged. We 

 thought, at first, that it was a bramido, a subterranean 

 noise. Clouds speedily surrounded the base of the moun- 

 tain ; they rose towards us slowly. No time was to be lost, 

 for it was necessary for our safety that we should pass the 

 difficult portion of our journey before being enveloped in 

 the cloud . A heavy fall of snow, or a frost, rendering the road 

 slippery, would have sufficed to prevent our return, and we 

 should have had no alternative but to remain upon the ice. 

 The descent was difficult. After proceeding 300 or 400 

 metres (984 or 1,312 feet) we penetrated into the clouds. 

 A little lower, sleet began to fall, which cooled the air 

 considerably ; and when we arrived at the place where the 

 Indian was who had charge of our mules, the cloud poured 

 upon us hailstones so large as to produce a very painful 

 sensation when they struck us on the hands or face. At 

 three quarters past four I opened my barometer, at Pedron 

 del Almuerzo, where in the morning at nine o'clock, it 

 stood at mm 



457,6 Therm. 50°- F. Air 42° 

 458,2 „ 40°-6 „ 39 



Difference 6 



It is remarkable that, at this height, the diurnal varia- 

 tion of the barometer is inverse, that is to say, that from 9 

 o'clock to 4, the barometer has ascended instead of de- 

 scended, as constantly occurs between the tropics. This ir- 

 regularity, however, is perhaps owing to some accidental 

 circumstance. I am more disposed to believe this, because, 

 at the farm of Antisana, I found that these variations were 

 less extensive than in the plain ; but I have observed, also, 

 that they took place in the same way. 



In proportion as we descended, sleet was mixed with the 

 hail. Night overtook us on the road, and it was 8 o'clock 

 before we reached the farm of Chimborazo. 



The observations which I have been able to make on this 

 excursion tend to confirm the idea which I have expressed 

 in another publication, for I have seen the same phenomena 



