200 THE TIMBER CARRIAGE. 



simple mechanical powers^ must have lain and 

 rotted where it fell. 



The lads turned inquiring eyes towards us ; 

 and I then said^ that these pulleys were ex- 

 actly on the same principle as those of the old- 

 fashioned wind-up jacks^ the weight of one of 

 which I remembered to have seen hanging 

 from Mrs. Heathfield's house. The mecha- 

 nical principles by which this astonishing force 

 was gained^ I did not attempt to explain^ be- 

 cause they could not be understood^ without a 

 measure of mathematical knowledge^ which it 

 was impossible^ at their early age^, they should 

 possess. 



We next examined the carriage^ and found 

 that it was composed of nothing more than 

 two pair of very strong wheels, kept in their 

 proper places by a very long and strong beam 

 of oak-timber. 



