560 



TRANSACTIONS OFTHE AMERICAN INSTITUTE. 



The results on July 17th are perfectly irregular. Up to 10,000 feet the 

 decrease accords with the other day's experiments, but from 10,000 feet 

 the results are surprising*, and continue so up to more than 20,000 feet. 

 The numbers in the last column of the table (the means) show that the 

 average decrease of temperature in the first 5,000 feet, exceed 20 degrees 

 Fah., and in the next 5,000 feet, is but little more than 10 degrees. The 

 numbers in the lowest line of the table show that the average decrease 

 of the temperature for 25,000 feet of elevation, is 60| degrees Fah., 

 or an average of two degrees to 1,000 feet. From these results it seems 

 that two-fifths of the whole decrease of temperature in five miles, takes 

 place in the first mile, and therefore that the decrement is not uniform with 

 the increments of elevation. The principal results of his observations Mr. 

 Glaisher summed up as follows : "That the temperature of the air does 

 not decrease uniformly with height above the earth's surface, and that con- 

 sequently more elucidation upon this point is required, particularly in its 

 influence on the laws of refraction. That the humidity or moisture of the 

 atmosphere does decrease with the height with a wonderfully increasing 

 rate, till at height exceeding five miles the amount of aqueous vapor in the 

 atmosphere, is very small indeed." Mr. Glaisher also asserted that observ- 

 ations up to three miles high, or 16,000 feet, even of a delicate nature, can 

 be made as comfortably in a balloon as on the earth; that at heights ex- 

 ceeding four miles, they cannot be made quite so well because of the per- 

 sonal distress of the observer; that at five miles high it requires the exer- 

 cise of a strong will to make them at all. That up to three miles high any 

 person may go into the car of a balloon who is possessed of an ordinary 

 degree of self-possession. 



The results of Messrs. Glaisher and Coxwell's balloon ascent on the 9th 

 of October, 1863, from the Crystal Palace, near London, accompanied by 

 two Americans, are given as follows: "The ascension was made at 4.30 

 minutes P. M. ; at four hours forty-six minutes the height attained was 

 7,200 feet. They gradually sunk to 1,600 feet, at five hours thirty-six min- 

 utes; increased to 8,600 feet at six hours, and then rapidly descended to the 

 earth at 6.40 P. M., being absent two hours and ten minutes. The tempe- 

 rature was 54 degrees Fah. At starting it was at 32 degrees; the freezing 

 point at the height of 5,600 feet; it decreased to 29^ degrees at 7,200 feet; 

 it then increased to 44| degrees at 1,600 feet, and then decreased to 26 



