330 TRA VELS AMONGST THE ORE A T ANDES, chap, xviii. 



The sole difference between this eruption and others which had 

 been remarked of Ootopaxi, was, probably, only one of degree. If 

 the pipe of the Volcano — its channel of communication with the 

 depths below — had been filled with molten lava, a means of exit 

 would have been afforded which would have prevented this great 

 manifestation of energy. The outburst suggested explosion, — a 

 violent deliverance of confined force ; and I conjecture that the 

 steam which was constantly welling up, instead of being permitted 

 to escape freely, or by intermittent discharges, was more effectually 

 imprisoned than usual [in the manner suggested upon pp. 153-4], 

 and that thus the temporary quietude was produced which was 

 noted in the early morning. During this time the subterranean 

 forces were gathering strength, under constantly-increasing heat, 

 due to augmented pressure ; at last acquiring power sufficient to 

 burst through the barrier, and then issued in a blast of inconceiv- 

 able violence ; rushing in a few seconds from depths with heat 

 above the fusing-point of iron to cold beneath the freezing-point of 

 mercury, rending the solid rock through which it passed into 

 infinitesimal fragments, and driving millions of tons of this im- 

 palpable powder vertically in the air, twenty thousand feet above 

 the lip of the crater. 



The new readings of the barometer on the summit of Chim- 

 borazo, agreeing closely with those which were taken upon the 

 first ascent, gave assurance, whilst still in the country, that there 

 was no material error in the measurements of atmospheric pressure 

 which had been made in the interior of Ecuador ; and the altitude 

 which has been deduced from them for Chimborazo, by nearly 

 according with that which was obtained from the previous obser- 

 vations, renders it probable that the accepted height of that 

 mountain is too great hy about 927 feet} 



For a second time we saw the barometer standing nearly as 



low as 14 inches, without experiencing what I have ventured to 



term the acute symptoms of mountain - sickness ; and, by a con- 



1 See Chapter XIX. for some further remarks upon the height of Chimborazo. 



