THROW-TESTING MACHINE FOR REVERSALS OF MEAN STRESS. 273 
from two large glass vessels supported by brackets fixed to the wall behind the 
machine. The oil was led by means of two f-inch brass pipes to the machine, one 
pipe being arranged to feed into a brass cup at the extremity of the crank pin, the 
other having a number of branches passing to the various bearings in the upper part 
of the machine. 
The brass cup supplies the oil to the crank pin by centrifugal force, by means of a 
hole passing along parallel to the centre line of the shaft and then at right angles 
into the crank pin bearing. The two pins in the horizontal connecting rod were 
supplied with oil from two vertical pipes having cups to receive the oil at their upper 
extremities, which pipes are connected together and oscillate about a pin supported 
by a bracket attached to the frame of the machine. From one pipe the oil is led 
directly up the centre of the pin connected to the horizontal sliding piece, and from 
the other the oil is led to the same pin but passes along a pipe attached to the 
connecting rod to the pin at the other end of the rod. 
Sheet iron shields are placed about the revolving parts, and these collect the oil 
thrown off, carry it down the vertical rod, and allow it to drain into a cup and pipe 
for carrying the oil so drained to the lower pin of this rod. The bearing of the 
vertical sliding piece, above the load, receives the oil drained from the upper parts of 
the machine ; the bearing below the load receives the oil from passages cut in the 
sliding spindle through which the oil passes on its downward course. The crank 
shaft bearings and the horizontal sliding piece bearings have each a separate oil 
supply pipe. 
A sheet iron trough is inserted between the frame of the machine and the bed- 
plate to catch the oil. The oil is taken out of the troughs, passed through a filter, 
and again used. The thick oil was used for nothing but the crank pin for some time, 
but, owing to the mixing of the oils in the lower trough, the oil all became gradually 
of a heavy variety, so that in about a few months the same oil was used for all the 
bearings. 
The machine, it was found, worked well after a few months’ running, but on 
changing from slow to high speeds, or vice versa, a little trouble was always 
experienced owing to the bearings heating. To help to keep the crank shaft 
bearings cool,—as it was these bearings which heated most easily,—a hole was 
drilled right through the whole length of this shaft, and a brass junction was 
specially made for the back end ; to this junction an india-rubber pipe conveying a 
stream of water was connected. The water passed along the hole in the crank shaft 
to the front of the machine, where, on passing out, it was received by a pipe of 
larger diameter, through which it was drained away. 
Determination of Stress. 
If W is the weight below the specimen, It the radius of the crank, L the length 
of the vertical connecting rod, w the angular velocity of the crank pin, and A the 
VOL. CXCIX.—A. 
N 
