Mechanical PhilosophT/. 43 



tryman, the Rev. Dr. Prince, of Salem/ Lavoi- 

 sier, and finally by Cuthbertson, of Amsterdam; 

 by the last of v^hom, we are taii^^ht to believe, this 

 machine has been carried to a degree of perfection 

 beyond which little advancement is to be expected. 

 That part of pneumatics, also, which relates to the 

 construction of Chimnies, the comfort of human 

 habitations, and the oeconomy of fuel, has been, in 

 modern times, the subject of much inquiry, and 

 most useful improvement, by Dr.DESAcuLiERs and 

 Mr. Anderson, of Great-Britain, and by the illus- 

 trious Americans Franklin, Count Rumford, and 

 many others. To which may be added a number, 

 almost countless, of wind instruments and ma- 

 chines, which modern ingenuity has invented, and 

 which have grown out of our increasing knowledge 

 of the qualities and laws of the important fluid 

 in which we ar^ immersed. 



In this period, beyond all doubt, we are to 

 place the invention of Balloons. In 1766, the 

 Hon. Henry Cavendish discovered that inflam- 

 mable air (the hydrogen gas of the French nomen^ 

 claturists) was at least seven times lighter than 

 common air. It soon afterwards occurred to the 

 celebrated Dr. Black, that if a thin bag were filled 

 with this gaseous substance, it would, according 

 to the established laws of specific gravity, rise in 

 the common atmosphere; but he did not pursue 

 the inquiry. The same idea was next conceived 

 by Mr. Cavallo, to whom is generally ascribed 

 the honour of commencing the experiments on this 

 subject. He had proceeded, however, but little 

 way in these experiments, when the discovery of 

 Stephen and John Montgolfier, paper manu- 

 facturers of France, was announced in 1782, and 

 arrested the attention of the philosophical world. 



I See the Transactions of the Aracr, A^ad. of Arts and Sciences, vol u 



