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III. The Defcriptlon of a new and fafe Crane , 
which has four different Powers ; invented 
by Mr. James Fergufon, F. R. S. 
Read Jan. 19, H E common crane confifts only of 
1 + JL a l ar g e wheel and axle; and the 
rope, by which goods are drawn up from fhips, winds 
or coils round the axle, as it is turned by men walk- 
ing in the wheel. But, as thefe engines have nothing 
to flop the weight from running down, if any of 
the men happen to trip or fall in the wheel, the 
weight defcends, and turns the wheel rapidly back- 
ward, and toffes the men violently about within it ; 
which has produced melancholy inftances, not only 
of limbs broke, but even of lives loft, by this ill- 
judged conftrudtion of cranes. And befides, they 
have but one power for all forts of weights ; fo that, 
they generally fpend as much time in raifing a fmall 
weight as railing a great one. 
Thefe dangers and imperfedlions made me think 
of a method of remedying them. And for that 
purppfe, I have contrived a crane with a proper flop 
to prevent the danger, and with different powers 
fuited to different weights ; fo that there might be 
as little lofs of time as poftible : and alfo, that when 
heavy goods are let down into fhips, the defcent may 
be regular and deliberate. 
This crane has four different powers : and, I be- 
lieve, it might be built in a room eight feet in width ; 
the gib being placed on the outfide of the room. 
Three 
