98 



THE APPLICATIONS OF PHYSICAL FORCES. [BOOK i. 



instruments, and the efficacy of their working, depend especially on 

 the skill and experience of the aeronaut. 



A short time after the invention of balloons, the idea was conceived 

 of using, in case of accident, a special apparatus, known as a para- 

 chute ; this had -been thought of a long time before. It is a kind of 

 dome, formed of spindle-shaped pieces of stuff sewn together, which 

 folds up and opens like an umbrella. Suspended either at the lower 



Via. ill A liallnon fitted with its i>ara-liutr. 



part of the balloon or near its equator, it is attached to the car by a 

 system of cords, arranged so as to carry this with its cargo as soon as 

 the rope is cut by which it is suspended. The parachute at first is 

 precipitated with increasing velocity, but the resistance of the air 

 gradually and completely unfolds its surface, and the whole system 

 can then descend gently to the ground. The parachute is very little 



