AERONAUTIC VOYAGES. 349 



These figures certainly demonstrate that, in high atmospheric regions, the ther- 

 mometnc variations are not less considerable than on the surface ot' the earth, and 

 that, in any case, if there be a stratum of constant temperature in the terrestrial 

 atmosphere, the fact of its existence is only admissible as regards an elevation 

 probably much greater than any yet reached. Is it practicable to transcend 

 this limitary height of 7,000 meters, by which all ascensions hitherto undertaken 

 have been bounded ? There is but one consideration which can make us hesi- 

 tate to answer affirmatively. We know not if man's physical constitution could 

 adapt Itself to a pressure much lighter than that of 311 mUlimeters, about two- 

 fifths of the mean pressure observed on the sea-shore. 



AN ACCOUNT OF BALLOON ASCENSIONS. 



BY MR. JAMES GLAISHER. 



• IFrom the London Athcnmim, October, 1864.] 



The committee on balloon experiments was appointed last year for the fol- 

 lowing purposes : To examine the electrical condition of the air at diiferent 

 heights ; to verify the law of the decrease of temperature ; and to compare the 

 constants in different states of the atmosphere. With respect ' to the first of 

 these objects no progress had been made, with the exception of preparing an in- 

 strument and apparatus for the investigation. At the request of the committee Mr. 

 Fleming Jenkin undertook the construction of the best instrument for the purpose, 

 and one was finished towards the end of 1SG3, but it was constructed to be used 

 "with fire. It has since had to be adapted for water, a constant flow of which is neces- 

 sary in electrical experiments in balloons. This apparatus Mr. Glaisher was re- 

 quested by the committee not to use, as they felt that these instruments, if exert- 

 ing no influence while the balloon was rising, might, when it was falling, throAV 

 considerable doubt on the experiments relating to humidity. With respect to the 

 second of these objects, the verifying the law of the decrease of temperature in 

 different states of the atmosphere, the committee considered would be best at- 

 tained by taking as many observations as possible at times in the year, and at 

 tipies in the day, at which no experiments had been made, for the purpose of 

 determining whether the laws which hold good at noon apply equally well at 

 all other times of the day. The committee have always pressed the importance 

 of magnetic observations in the higher regions of the air — the Astronomer lioyal 

 suggesting the use of a horizontal magnet, and taking the times of its vibration 

 at different elevations, a method which is seldom practicable, owing to the al- 

 most constant revolution of the balloon. To obviate this. Dr. Lloyd suggested 

 the use of a dipping-needle, placed horizontally when on the ground, by means 

 of a magnet above it, so that, w^hen in the balloon, the deviation from horizon- 

 tality might be noticed, and which deviation would be independent of rotary 

 motion of the balloon. The latter method has not yet been tried. Dr. Lloyd 

 wishing some experiments to be made before the instrument was constructed. 

 At Newcastle a very general wish being expressed that very high ascents 

 should not again be attempted, none above five miles had since been made. Mr. 

 Glaisher then gave an account of the ascents made by him during the past year. 

 The first was from Newcastle, on the 31st of August. The balloon left the earth 

 at 6h. 11m. p. m., with a north wind, 'and descended. at five minutes past 7, at 

 Pittington, near Durham. The decrease of temperature within the first SQO 



