On the Lofty Fit gM of' the Condor. 143 



at a height where the mean pressure of the air is only 14 inches.* 

 It was then imagined, from the analogy of experiments made 

 with the pneumatic machine, that no animal could live in so rare 

 a medium. I have seen the barometer fall on Chiniborazo to 

 13 inches W^o '^"^s. My friend, M. Gay Lussac, respired for a 

 quarter of an hour in an atmosphere whose pressure was only 

 ^".SSSS. At heights like these, man in general finds himself 

 reduced to a most painful state of debility. In the Condor, on 

 the contrary, the act of respiration appears to be performed with 

 equal ease, in mediums where the pressure differs from 12 to 30 

 inches. Of all living beings, it is without doubt the one that 

 can rise at will to the greatest distance from the earth''s surface. 

 I say, at will, because small insects are carried still higher by 

 ascending currents. Probably the height which the Condor at- 

 tains is greater than that which we have found by the calcula- 

 tion mentioned above. I remember that on Cotopaxi, in the 

 Plain of Suniguaicu, covered with pumice, and elevated 13,578 

 feet above the level of the sea, I perceived that bird at such 

 a height, that it appeared like a black dot. What is the smallest 

 angle under which objects weakly lighted are distinguished .^-f- 

 The diminution which the rays of light undergo by passing 

 through the strata of the atmosphere, has a great influence upon 

 the minimum of the angle. The transparency of the air of 

 mountains is so great under the equator, that, in the province of 

 Quito, as I have elsewhere shewn;^, the poncho or white mantle 

 of a person on horseback is distinguishable at a horizontal dis- 

 tance of 84,032 feet, and consequently under an angle of 13 

 seconds. 



• Astronomical observations inade by order of the King of Spain, p. 109. 



f It is probably one minute. In 1800, a balloon, which was four fathoms 

 in diameter, was seen Avith the naked eye at Berlin to fall at a distance of 

 40,200 feet. It was then under a visual angle of 2*4". But it could have 

 been distinguished at a much greater distance, notwithstanding the consti- 

 tution of our northern atmosphere. 



X In ray memoir on the diminution of heat, and on the lower limit of per- 

 petual snow. 



llumholdt, TaUeaux de la Nature, t. ii. pp. 72>»78k 



