LEAP FROM A CARRIAGE* 135 



VIII. 



Invcsiig(dlon of the Principles which shezo that it would 

 be much safer to Jump from the Back than from the 

 Side of a Carriage when run away with hy unruly 

 Horses. In a Letter from J. E. Con ant, Esq. Sfc. 



To Mr. Nicholson. 



Great Marlborough Street, Sept. 17. 

 Sir, 



-S so many accidents continually happen from the de- It is more ad- 

 structive expedient of leaping from the side of an open 7J^^ ^^^^ ^j^^ 

 carriage while the horses are running away with it, per- back than from 

 haps you may be induced to insert this in the Philoso. ^^^ }^^^. ^^ ^ 

 phical Journal, in which I attempt to determine how far tjon. 

 it may be safe in such cases to leap from the back of the 

 vehicle. I hope it will be found correct, but I submit it 

 with due deference to yourself and others. 



In the following calculation, setting aside the resist- Estimate of the 

 ance of the air, 1 suppose a young man (for it is a young 7^*°^."y °* 

 practice to put an unruly horse to a carriage) able to 

 spring tw*t> feet perpendicularly against the force of gra- 

 vity ; but in falling one second, he, in common with all 

 bodies, would acquire a velocity of 32 feet per second, 

 and have fallen through a space of 16 feet ; and the spaces 

 described being as the squares of the velocities, a man in 

 falling 2 fdet acquires a velocity of 11 feet per second, 

 and this equals the velocity with which he first springs 

 from the ground. 



Suppose the carriage is moving at the rate of 12 miles A man can 

 an hour, and a man springs from the back of it at an JJ^^P ^'*^ ^^ 

 angle of about 40° from the horizon with a force as locity of six 

 above equal to about 1 1 feet per second ; this force esti- "^'^*^* ^" houTy 

 .mated horizontally will be about 9 feet per second, and 

 the effort of the air, so far from resisting, will be in 

 favour of the horizontal projection ; this 9 feet per 

 second, or 6 miles per hour, deducted from the 12 miles, 



leaves 6 miles per hour for the actual horizontal velocity which dc- 



of the man after his leap, which the force of the air will ducted from 

 somewhat lessen, .and this, with the accelerating force of eaJriage^ill 



gravity, leave six— 



