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balance weight, &c., and raised the weight to the same height as before; it came to 
TRANSACTIONS OF THE SECTIONS. 117 
directions to each other at high velocities. It will be found when an engine of 
20-inch strokes with 6 feet driving-wheels goes 15 strokes per minute or 3 miles 
per hour, it requires one-tenth of the weight moving along the horizontal line (that 
is, the pistons and gearing moving backwards and forwards within the engine-framing) 
to stop it and turn it again. 
At 35 strokes per minute, or about 7 miles per hour, one-half its weight; at 74 
strokes per minute, or about 15 miles per hour, 1} time its weight ; at 100 strokes 
per minute, or about 20 miles per hour, four times its own weight will be required 
forthe same purpose. By attaching a weight with connecting rod and an auxiliary 
crank to the head of the crank-pin, equal to the piston and its gearing, so as to make 
the weight run to the left-hand at the same instant the piston goes to the right, the 
blow to stop the piston and make it return at each end of the stroke will be received 
in the auxiliary crank instead of in the wheels, producing a neutral point in the 
centre and steadiness of motion ; for when the blow is received in the wheels, the 
cranks being at right angles, it is communicated through the axle and gives a twisting 
-motion to the whole framing of the engine; this being repeated with regularity, pro- 
duces an effect similar to the rocking of a boat. ‘This oscillation is found to be 
greatest when the engine is running most regular for speed and the piston going the 
same way with the oscillation of the carriage. The wire screwed to one of the piston 
frames with a loose piece of iron upon it, is intended to show at what speed the wire 
can move backward and forward before it begins to slip. Ifa weight be moved in a 
similar manner with a 20-inch stroke, it will slip at 35 strokes per minute, or less 
than 2 feetin a second; therefore, when it is considered that the pistons of locomotives 
frequently travel at the rate of 18 feet in a second, or come to a dead stop and turn 
again 10 times in a second, it must be evident that the blow is sufficient to make the 
whole engine oscillate and jump in a most fearful manner; when it is also considered 
that an engine running at 100 strokes per minute, or the pistons and gearing tra- 
velling at about 5} feet per second, require four times their own weight to stop them 
and turn them again, when the weight of each piston, &c. frequently exceeds 400 
unds. 
P'To prove that the steam has no action in causing the oscillation, but merely to 
blow the different bodies apart, I bored a small hole in the middle of a gun-barrel, 
and placed 2 pieces of iron weighing 20 ounces each, which fitted the bore of the 
barrel up to each side of the hole. [ then puta few graias of gunpowder between 
them, the barrel being placed upon a bed of sand to show if it moved, and then fired 
the gunpowder ; the pieces of iron were each blown the same distance from the hole, 
and the barrel remained where it was placed. 
_ Experiment 2. I then placed 10 and 20 oz. in the same position as before, and 
fired, the barrel remaining still; the 10 oz. weight was blown 4 times the distance 
of the 20 oz. 
_ Experiment 3. I then placed 5 oz. and 30 oz. in the same position and fired it, the 
barrel remaining still, but the 5 oz. weight was blown 40 times the distance of the 
30 oz. 
The oscillations of the machine do not increase in violence regularly as the speed 
increases, for if the pistons do not keep time with the oscillations of the machine, it 
is then tremulous motion until the pistons go with the machine every second stroke, 
and so on to any speed, similar to a railway train that will shake violently when 
running along a straight level line at about 23 or 24 miles per hour; increase the 
‘speed 2 or 3 miles per hour, it will become nearly steady ; by further increasing the 
speed the oscillation becomes again violent, just as the whole weight of the engine 
the whole weight moved. \ 
_ In making some experiments with this machine I raised 10 cwt. 16 feet high, and 
attached it to the shaft the handle is upon, and then let it run down; it came to the 
_ floor in 242 seconds. I then attached the auxiliary crank with connecting rod, 
4 can oscillate in proportion to the weight of the piston and its gearing compared with 
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_ the floor in 210 seconds, although adding so many more moving joints the friction 
_ Of which had to be overcome. 
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