17 U PNEUMATICS. 



by its means much addition to our knowledge of 

 the atmosphere, owing partly to the recentness of 

 the discovery, and partly to a deficiency of philo- 

 sophical knowledge in most of the adventurers. 



The agreeable stillness and tranquillity aloft in 

 the atmosphere have been matter of general ob- 

 servation. On arriving at a considerable height, 

 great cold has always been experienced; and clouds 

 have been passed through, which contained some- 

 times snow, and sometimes lightning. The view 

 of the country below is said to be inconceivably 

 grand. 



Upon the whole, considering the number of voy- 

 ages that have been made, but few accidents have 

 happened; and these were commonly owing to the 

 bad construction of the apparatus. The balloon 

 seems, when properly managed, to be quite as safe 

 as any other species of conveyance. 



On the Mode of Constructing and Filling Balloons. 



There are, as has been already mentioned, two 

 kinds of balloons ; those raised with heated, or 

 rarefied air, and those filled with inflammable air. 



The best forms for balloons are, that of a globe, 

 and an egg-like figure. Fire-balloons, or those 

 raised by heated air, if very large, may be made of 

 linen, or silk ; and must be open at bottom, having 

 a hoop round the opening, from which is suspended 

 the grate for the fuel, which is best of straw, or 

 other light combustibles. Small balloons of this 

 kind may be made of tissue-paper, having a wire 

 round the bottom. Two cross wires may support in 

 the centre of the opening a little cup, with some 

 cotton and spirits of wine, the flame of which will 

 rarefy the air, and raise the machine. 



