54 Mechanical Philosophy. [Chap. I. 



did not pursue the inquiry. The same idea was 

 next conceived by Mr. Cavallo, to whom is gene- 

 rally^ ascribed the honour of commencing the ex^ 

 periments on this subject. He had made but little 

 progress, however, in these experiments, when 

 the discovery of Stephen and John Montgolfier, 

 paper-manufacturers of France, was announced in 

 1 782, and engaged the attention of the philosophi- 

 cal world. Observing the natural ascent of smoke 

 and clouds in the atmosphere, those artists were 

 led to suppose that heated air, if enclosed in a 

 suitable covering, would also prove buoyant. Ac- 

 cordingly, after several smaller experiments, by 

 which this idea was fully confirmed, they inflated 

 a large balloon with rarefied air, on the 5th of 

 June, 1783, which immediately and rapidly rose 

 to the height of six thousand feet, and answered 

 their most sanguine expectations, It was soon 

 found that machines of this kind might be so con- 

 trived as to convey small animals, and even human 

 beings, through the air with ease. The first hu- 

 man adventurer in tjiis aerial navigation was M. 

 Pilatre de Rozier, a daring Frenchman ; who rose 

 in a large balloon, froni a garden in the city of 

 Paris, on the 15th of October, 1783, and remained 

 a considerable time suspended in the air. He 

 rnade several aerial voyages of greater extent after- 

 wards, and in two of them was attended bj other 

 persons. In a short time, however, the use of rare- 

 fied air in aerostation was, for the most part, laid 

 aside, as inconvenient and unsafe^ and recurring 

 once more to the discovery of Mr. Cavendish, the 

 philosophers of Paris concluded that a balloon, in- 

 flated with inflan^imable air, would answer all the 



