320 DR. FAIRBAIRN ON THE EFFECT OF IMPACT, VIBRATORY ACTION, 
Table II. — Experiment on tlie same beam with a load equivalent to two-sevenths of 
the breaking-weight, or nearly 3-| tons. 
Date, I860. 
Number of 
changes of load. 
Deflection, in 
inches. 
Bemarks. 
May 14. 
0 
0-22 
In this Table the number of changes of load is 
15. 
12,623 
0-22 
counted from 0, although the beam had already 
17.’ 
36*417 
0-22 
undergone 596,790 changes, as shown in the pre- 
ceding Table. 
19. 
53,770 
0-21 
22. 
85,820 
0-22 
26. 
128,300 
0-22 
29. 
161,500 
0-22 
31. 
177,000 
0-22 
June 4. 
194,500 
0-21 
7. 
217,300 
0-21 
9. 
236,460 
0-21 
12. 
264,220 
0-21 
16. 
292,600 
0-22 
9ft 
A()Q 01 A 
A.90 
f At this point the operations were suspended, the 
25 D. 
'±U0 5 25JLU 
U 250 
[ beam having suffered a million changes of load. 
The beam had now sustained one million changes of load without any apparent 
injury ; it was then considered necessary to increase the load to 10,486 lbs., or two- 
fifths of the breaking-weight, when the machinery was again put in motion. With 
this additional weight the deflections were increased, with a permanent set of *05 inch, 
from -23 to *35, and after sustaining 5175 changes, the beam broke by tension a short 
distance from the middle. It is satisfactory here to observe that during the whole of 
the 1,005,175 changes none of the rivets were loosened or broke. 
Table III. — Beam repaired. 
The beam fractured in the preceding experiment was repaired by replacing the broken 
angle-irons on each side, and putting a patch over the broken plate equal in area to the 
plate itself. Thus repaired, a weight of three tons was placed on the beam, equivalent 
to one-fourth of the breaking-weight, when the experiments were again continued as 
before. 
