104: Accoiint of the Aerial Voyage 



was placed in me, I embraced it with pleasure; and, after 

 (he acconiplisliment of the excursion, I now have the ho- 

 nour of laying before the academy the following account of 

 the experiments and observations I made. 



The experiments proposed by the academy, which were 

 to be made at the greatest distance from the earth, have 

 been already described by several aeronauts, but have been 

 either doubted or entirely rejected : as for example, tiie 

 faster or slower evaporation of fluids ; the decrease or in- 

 crease of the magnetic force ; the inclination of the mag- 

 netic needle ; the increase of the power in the solar rays to 

 excite heat ; the greater faintntss of the colours produced 

 by the prism ; the existence or non-existence of the electric 

 matter; some observations on the influence and changes 

 which the rarification of the air occasions in the human 

 body; the flying of birds; the filling with air, flasks ex- 

 hausted by Torricelli's method, at each fall of an inch in 

 the barometer; and some other chemical and philosophical 

 experiments. 



The instruments I carried with me for these experiments 

 were : 



1st, Twelve flasks in a box with a lid. 



2d, A barometer and thermometer. 



3d, A thermometer. 



4th, Two electrometers, with sealing-wax and sulphur. 



5th, A compass and magnetic needle. 



6th, A watch that beat secoi^ds. 



7th, A bell. 



8th, A speaking-trumpet. 



9th, A prism of crystal. 



10th, Unslaked lime, and some other things for che- 

 mical and philosophical experiments. 



But as no means have hitherto been found of ascertain- 

 ing with certainty over what part of the earth a balloon is 

 hovering, and to what quarter it is driven by the wind, 

 especially when there are clouds below it, by which means 

 terrestrial objects cannot be seen, and where the aeronaut 

 in his car (where he is not sensible of the motion of the 

 balloon) cannot discover the direction of it for want of fixed 

 objects of comparison, I employed the two following me- 

 thods to ascertain to which side it was impelled by the wind : 



1st, I fixed perpendicularly, in an aperture made in the 

 bottom of the ear, an achromatic telescope, which showed 

 me very distinctly those terrestrial objects over which the 

 balloon happened to be, and to which side it directed its 

 course. 2d, I laid together, cross-wise, two sheets of black 



paper ; 



i 



