NATURAL PHILOSOPHY. 143 



wind was not confirmed in our trips ; nor was the appearance of the 

 upper surface of the clouds such as to establish the theory that the 

 clouds assume a counterpart of the earth's surface below, and rise or 

 fall like hills and dales." 



The principal results of his observations Mr. Glaisher summed up 

 as follows : That the temperature of the air does not decrease uni- 

 formly with height above the earth's surface, and that, consequently, 

 more elucidation upon this point is required, particularly in its influ- 

 ence 011 the laws of refraction. That an aneriod barometer can be 

 made to read correctly, certainly to the first place, and probably to 

 the second place of decimals, to a pressure so low as five inches. 

 That the humidity of the atmosphere does decrease with the height, 

 with a wonderfully increasing rate, till at heights exceeding five 

 miles the amount of aqueous vapor in the atmosphere is very small 

 indeed. Mr. Glaisher also assorted " that observations up to three 

 miles high, even of a delicate nature, can be made as comfortably in 

 a balloon as on the earth ; that at heights exceeding four miles they 

 cannot be made quite so well, because of the personal distress of the 

 observer ; that at five miles high it requires the exercise 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. That no person with heart-disease or pul- 

 monary complaints should attempt four miles high. But, at the same 

 time, it must be borne in mind that I am concluding that the balloon 

 is properly handled." 



In the discussion that ensued, Mr. Glaisher read a letter from a 

 French scientist, M. Simons, offering to go eleven miles high, and in- 

 viting Mr. Glaisher himself to ascend eight and a half miles with him. 



CJ <~J 



Mr. Glaisher said he had no doubt that by taking up sufficient oxygen 

 a higher point might be attained, but he (Mr. Glaisher) thought the 

 risk too great. Colonel Sykes said that after Mr. Glaisher became 

 insensible, Mr. Coxwell must have risen to the elevation of at least 

 seven and a half miles, and was not otherwise affected than by the 

 cold benumbing his hands. He thought there was not, after all, so 

 much danger, and that the sensations experienced resulted from the 

 particular idiosyncracy of the individuals. He hoped the Association 

 would sanction further experiments, and they need be under no ap- 

 prehension as to the danger of higher ascents. Dr. Drosier thought 

 the utility of reaching high altitudes was undisputed. Several physi- 

 cal forces had contributed to the loss of sensation experienced by Mr. 

 Glaisher : the first and least effective was cold ; next, the diminution 

 of oxygen ; and, last and most important, the diminution of pressure 

 upon the surface of the body, and consequently of the pressure of the 

 blood upon the brain, which caused syncope. This he proposed to 

 remedy by a horizontal position, or more effectually by an air-tight 

 covering for the body containing atmospheric air, from which, how- 

 ever, the head might be excluded. 



In a recently published letter on Messrs. Giaisher and Coxwell's 

 aerial experiments, Sir John Herschel says : While congratulat- 

 ing these gentlemen on the narrow escape with their lives from so 

 unheard-of a fate as tnat which awaited them had Mr. Coxwell's teeth 

 been ever so little less tenacious, I must be allowed to demur to the 



