95 
Steam Engine. 
motion, by a chain going round a pully, and also round 
two barrels furnished w ith ratchet wheels, with a weight 
suspended to the free end of the chain, which served to 
continue the motion during the return of the engine. In 
1778, Mr. Matthew Washbrough also obtained a patent 
for communicating a rotative motion from the steam en- 
gine, by a method which w^as virtually the same as that at 
Hartley ; only, he had added a fly-wheel, which be- 
lieve was then for the first time employed in the steam 
engine, though it is evident, from the letter we have quot- 
ed from Mr. Watt to Dr. Small, that the former had con- 
ceived the idea long previous to this period. Two or 
tliree of these engines were erected ; but, owdng to the 
defective mode of communicating the motion, were sub- 
ject to such irregularities and accidents, as rendered them 
of little use. 
The idea of communicating motion from the beam of 
the steam engine to a crank, in the same manner as is done 
in the common foot-lathe, had, as we are informed, early 
occurred to Mr. Watt ; but we believe he did not se- 
riously set about reducing his ideas to practice until the 
year 1778 or 1779. In the first model he then made, in 
order to equalize the power, tw^o cylinders, acting upon 
two cranks were fixed upon the same axis, at an angle of 
120 degrees from each other ; and a weight vras placed 
upon the circumference of the fly-wlieel, at an angle of 
120^ from eachol the cranks ; which weight was to be so 
adjusted, as to act when neither of the cranks could do so, 
and consequently to render the power nearly equal. This 
model performed to satisfaction ; but Mr. Watt having 
neglected to take out a patent immediateqg the essential 
part of tlie contrivance w^as communicated, as we under- 
stand, by a workman employed to make the model, to the 
persons engaged about one of Washbrough ’s engines ; 
and a patent was taken out for tlie application of the crank 
