IN SOUTM-AMERICA, 



215 



rains to which the traveller is fubjed on the way, and which render the roads almoft 

 impaflable even in the fineft feafon, as of the difficulty and danger attending the cele- 

 brated pafs on quitting the Cordilleras called Pongo. Principally that I might furvey 

 this pafs, which is never fpoken of at Quito without admiration and dread, and that I 

 might lay down on my chart the whole navigable extent of the river, I feledted of 

 the three roads, the laft. 



I left Tarqui, the fouthern extremity of our meridian, five leagues fouth of Cuenca, 

 on the I Jth of May 1743. On my journey to Lima in 1737, I travelled the cuftom- 

 ary road from Cuenca to Loxa ; on this occafion I went by a circuitous one, paffing 

 by Zaruma, in order to place that fpot on my map. I ran fome riik in fording the 

 great river Los Jubones, then much fwollen, and always very rapid, but by chofing 

 this courfe I avoided a greater ; as I have fmce been given to underftand, alTaffins em- 

 ployed by the authors of, or accomplices in the murder of our furgeon, laid in wait for 

 me on the high road from Cuenca to Loxa. 



From a mountain over which I pafled on my way to Zaruma, Tumbez is diflin- 

 guifhed, a port on the South-Sea, at which the Spaniards effedled their firft landing, 

 fouth of the Hne, on their expedition for the conquefl of Peru. From this point it 

 was that I began to turn my back on the South-Sea, and take an eaftward courfe acrofs 

 the continent of South-America. This place was formerly celebrated for its mines, 

 now almofl abandoned. The gold extracted is much alloyed, being no more than 

 fourteen carats fine ; it is mingled with filver, and very duftile. 



At Zaruma the barometer flood at 24 inches two lines ; unlike in our climates, 

 beneath the torrid zone it is fubjecSl to little variation ; for at Quito we found that 

 the extreme difference, in the fpace of feveral years, did not exceed a line and a half. 

 Mr, Godin was the firft who remarked that the variations of the barometer, which in 

 the courfe of four and twenty hours extend to about a line, are fubje£t to pretty regu- 

 lar alterations, which, once known, allow the afcertainment of the mean height of the 

 mercury by a fingle experiment. The different experiments made by me on the 

 fhores of the South-Sea, and thofe I repeated on my journey to Lima, fatisfied me what 

 this mean height was at the level of the fea, whence I was enabled to aflign with tole- 

 rable exactitude an elevation of 700 toifes (about 4400 Englifh feet), to the territory 

 about Zaruma, an elevation not half fo great as that of the land about Quito. In this 

 calculation I made ufe of atable computed by M. Bouguer, after an hypothefis, 

 which has hitherto correfponded better than any other with experiments made with the 

 barometer, and verified by trigonometrical meafurement. I came from Tarqui, a 

 region rather cold, and experienced great warmth at Zaruma, notwithftanding I was 

 fcarcely lefs elevated there than on Mont Pelce, in Martinico, where we found the 

 cold fevere, afcending from a low and warm country. I prefuppofe here that the 

 reader is apprized already of our having conflantly obferved, during our long 

 fojourn in the province of Quito, under the equinoctial line, that the elevation of the 

 foil almofl exclufively determines the degree of heat, and that it does not require one 

 fhould afcend fo high as 2000 toifes Cabout 12,600 Englifh feet), from a valley parched 

 by i^itenfe heat, to reach the foot of maffes of fnow, antient as the globe itfelf, with 

 which a neighbouring mountain is crowned. 



On my way, I croffed many bridges made with cords, bark of trees, or lianas. 

 Thefe lianas, netted together, form an aerial gallery, which is fufpended from two large 

 cables of fimilar materials, the extremities of which are faftened to branches of trees 

 on oppofite banks. Colledlively, the whole of thefe fingular bridges refembles a fifher's- 

 net, or rather an Indian hammock, extending from one to the other fide of the river. 



10 -As 



