156 Col. Francis Hairs Meteorological Observations 



variable; while the town of Ambato, only 300 feet lower than 

 Quito, but built in a nook of the river which runs near it, and 

 shut in by dry sandy elevations, has a climate about 2°*0 

 milder, so that sugar-cane is cultivated in its immediate vici- 

 nity. The treneral uniformity of temperature, which spreads 

 a certain monotony over tropical regions, is joined, at great 

 elevations, to a daily variability, which must exercise a consi- 

 derable influence both on vegetable and animal life. The 

 thermometer, which often sinks at night to 44°-0, rises in the 

 sun, wherever there is reflected heat, frequently to 120°'0, be- 

 ing equal to the heat of Jamaica ; while in the shade it seldom 

 exceeds 65°*0 : so that, on passing from shade to sunshine, 

 one is immediately exposed to a difference of above 50°'0, 

 and in the course of twenty-four hours to nearly 80°'0. The 

 shade, in consequence, even on the hottest days, imparts a 

 feeling of chilliness, while the solar rays seem to scorch like 

 the vapour of at heated oven. The same difference is per- 

 ceptible on the Paramos. At the foot of the Nevado of Santa 

 Marta, I observed the thermometer at 5 a.m. sink to 22'^-0, 

 and at 9 a.m. it rose to 73*°0 in the sun. On the height of 

 Pichan, between Quito and Esmeraldas, elevation 12,986 feet, 

 the thermometer stood at .53°*0 in the shade, and 83°'0 in the 

 sun. On Antisana the difference was 22°*0 at the same time, 

 but 34°-0 between 6 a.m. and 3 p.m. : when the atmosphere is 

 calm it is much more considerable. 



5. Although at great elevations, i. e, from 12,000 to 16,000 

 feet, it is difhcidt to form a series of meteorological observa- 

 tions, such is the yearly equality of the temperature that a 

 single day may be safely taken as a sample of the whole year. 

 Nay more, a collection of observations made at similar heights, 

 though in different places, will give a similar result to a series 

 taken on the same spot. Thus, in the following table, there 

 is little difference between the result of seven observations, 

 made on seven different mountains, and the six made on that 

 of Antisana. 



