12 Col. R. Wright's Meteorological Observations made 



the confines of this province. The whole Peruvian coast from 

 Pavta to Lima is an additional instance of the same fact, where 

 the recession of the Andes from the coast is marked by sandy 

 deserts which the industry of the Incas had rendei'ed product- 

 ive bv artificial irrigation. In the valleys and on the table- 

 lands'^of die mountains themselves the culminating summits 

 produce (^i-eat variations in the distribution of moisture. The 

 citv of Caraccas, situated at the foot of the Silla, has the be- 

 nefit of a regular though mild rainy season, while within a 

 league there are spots which suffer several years of drought. 

 Popayan, placed at the head of the sultry valley of the Cauca, 

 and surrounded by lofty jyarcwios, has nine months of con- 

 tinued rains and tempests, attributable to the clouds which 

 are driven in opposite directions from the mountains till they 

 encounter the hot ascending air of the valley. In the ancient 

 kinodom of Quito, now called the Republic of the Equator, 

 the mass of Chimborazo interrupts the passage of the clouds 

 from south to north ; so that, while the western slopes are de- 

 luded with rain, the elevated plains of Riobamba to the east 

 recall to the imagination of the traveller the deserts of Arabia 

 Petraaa. Following the same mountain chain towards the 

 city of Quito, we observe the storms arrested betwixt Coto- 

 paxi and Pichincha, over the valley of Chillo; while two 

 leagues further to the north the climate of the village of Po- 

 masqui is so dry as to have given it the name of Piurita (little 

 Piura). 



The manner in which rain is formed and precipitated at 

 various elevations, seems to illustrate and confirm the theory 

 of Leslie. In the region o^ paramos, i.e. from 12,000 feet 

 upwards, the encountering aerial currents, unless in the case 

 of some strong agitation of the mass of surrounding atmo- 

 sphere, are of a low and nearly equal temperature. The rains 

 in consequence assume the form of thick drizzling mists, known 

 bv the name of jmramitos. On the elevated plains we find 

 the showers more or less sudden and violent, according to lo- 

 calities which give rise to a mixture of currents more or less 

 variably heated. Quito, for example, is situated on what may 

 be called a ledge of the lofty mountain of Pichincha, and 

 overlooks the valley of Chillo or Guaillapamba, furrowing the 

 adjacent table lanil, on which the thermometer often rises to 

 80" in the shade. The encounter of portions of the atmo- 

 sphere, thus variously heated, produces showers as ^sudden 

 and heavy as those which generally distinguish tropical cli- 

 mates. On the slopes of the Cordillera the rains are generally 

 violent for the same reason. Looking to the hygrometrical 

 state of the atmosphere, as it results from observations made 



