:bouguer's voyage to peru. 295 



thermometer placed In the fhade, and afterwards in the fun, undergoes in no weather or 

 place any proportional alteration. Upon Pichincha, this inftrument commonly ftands 

 in the morning fome degrees below the freezing point, which mufl be regarded as the 

 natural temperature of the ftation ; but let this inftrument be expofed during the day 

 to the fun, it is not difficult to conceive the effect will be very great, and much more 

 than double in whatever manner meafured. 



There remains another object, the laft to be confidered on this fubjed, which is, to 

 explain why fometimes we experience an excefs of cold, while the thermometer indicates 

 but a moderate degree of it. It feems that three or four degrees, at which this inftru- 

 ment ftands below the freezing point, does not correfpond with all the inconvenience, 

 it is better to fay, with all our fuffering : but we ought to recoiled that we had left a 

 very temperate climate, of which we had made to ourfelves, as it were, a new country, 

 and that our removals into another had always been very fudden. It is known from 

 daily experience, in the countries we fpeak of, that the heat and cold are but relatively 

 great, and that our prefent difpofttion depends in a great meafure on the place we have 

 quitted. When we afcend or defcend the Cordelier, and pafs the places elevated fix or 

 feven hundred toifes above the fea, we feel the cold or heat in the fame place, as we may 

 happen to have come from below or above it ; if from below, we are cold ; on the 

 contrary, we are in the moft violent perfpiration when, coming down from an height on 

 which it freezed. 



We had already remarked fomething fimilar to this, when in our own iflands we had 

 to afcend the higheft of the mountains there. After a journey of five or fix hours at 

 Martinique, we attained the fummit of Pelee at one o'clock in the afternoon, and we 

 were fhivering with cold, although the thermometer ftood yet at 17I degrees above the 

 freezing point : it is even neceflary our refidence in any place ftiould be of confiderable 

 length, to know that we could make it our conftant one ; and this proves that our pores 

 do not eafily undergo an alteration, and that we do not all at once take a difpofition of 

 body congenial with each climate. Here we may difcern the caufe of all thofe unfor- 

 tunate accidents happening at times to thofe obliged to pafs over fome very high ridge 

 or defile on leaving or entering the Cordelier. By the interception of the wind 

 by the mountain we find a fpecies of fhelter, and enjoy a temperate climate in our afcent ; 

 but no fooner have we reached the ridge, than we are all at once feized on by the cold, 

 rendered incomparably fharper by the frozen particles carried by the impetuofity of 

 the wind that rifes upon us. Let it be refleded how much the hafte of this change 

 differs from the flownefs with which our different feafons are brought on, and the dan- 

 ger to which we are expofed under fuch circumftances will be the better imagined. I 

 have had alfo more than once or twice occafion to remark, that a very little difference of 

 elevation in very high ftations make a very confiderable one in their temperature : fome- 

 times the weather where I have been ftationed has been but moderately unfavourable. 

 When at thirty or forty toifes above me on the part of the mountain covered with fnow, 

 on which the ftorm feemed moft to prefs, I could clearly behold it was very different, f 

 Some travellers have only been able to preferve themfelves, when the ftorm has been of 

 ihort duration, by ripping up the belly of their horfes, and fheltering themfelves in 

 them. 



I have already mentioned a paffage at the foot of Chimborazo," abpve the Guaya- 

 quil, or Caracol : but there is another pals, infinitely more to be dreaded, and is the 

 mofl famed in all South America ; it is named the Pafs of Gouanacas, fituated in 

 1° 34' N. latitude, between Popayan and the little town of Plata. This pafs conducts 



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