SUPPLEMENT 



The Description of a neiu and safe. Crane, which has four 

 different Poivers, adapted (o different Weights. 



THE common crane consists only of a large wheel 

 and axle ; and the rope, by which goods are drawn up 

 from ships, or let down from the quay to them., winds or 

 coils round by the axle, as the axle is turned by men 

 walking in the wheel. But, as these engines have no- 

 thing to stop the weight from running down, if any of 

 the men happen to trip or fall in the v heel, the weight 

 descends, and turns the wheel rapidly backward, and 

 tosses the men violently about within it ; which has 

 produced melancholy instances, not only of limbs broken, 

 but even of lives lost, by this ill-judged construction 

 of cranes. And besides, they have but one power for 

 all sorts of weights ; so that they generally spend as 

 much time in raising a small weight as in raising a great 

 one. 



These imperfections and dangers induced me to 

 think of a method of remedying them. And for that 

 purpose, I contrived a crane with a proper stop to pre- 

 vent the danger, and with different powers suited !<> 

 different weights ; so that there might be as little loss 

 of time as possible : and also, that when heavy goods 

 are let down into ships, the descent may be regular and 

 deliberate. 

 This crane has four different powers : and, I believe. 



