AND LONG-CONTINUED CHANGES OE LOAD ON WROUGHT-IRON GIRDERS. 319 
The beam having been loaded with 6643 lbs., equivalent to one-fourth of the ultimate 
breaking- weight, the experiment commenced as follows : — 
Table I. — Experiment on wrought-iron beam with a changing load equivalent to one- 
fourth of the breaking-weight. 
Date, 1860. 
Number of 
changes of load. 
Deflection pro- 
duced by load. 
Remarks. 
March 
21. 
0 
0-17 
39 
22. 
10,540 
0-18 
23. 
15,610 
0-16 
24. 
27,840 
Strap loose, and failed to lift the weight. 
26. 
46,100 
o-ie 
27. 
57,790 
0-17 
28. 
72,440 
0-17 
29. 
85,960 
0-17 
30. 
97,420 
0-17 
31. 
112,810 
0-17 
April 
2. 
144,350 
0-16 
4. 
165,710 
0-18 
99 
7. 
202.890 
0-17 
99 
10. 
235,811 
0-17 
99 
13. 
268,328 
0-17 
99 
14. 
281,210 
0-17 
99 
17. 
321,015 
0-17 
20. 
343,880 
0-17 
The strap broke. 
25. 
390,430 
0-17 
99 
27. 
408,264 
0-16 
99 
28. 
417,940 
0-16 
May 
1 . 
449,280 
0-16 
3. 
468,600 
0-16 
99 
6. 
489,769 
0-16 
99 
7. 
512,181 
0-16 
99 
9. 
536,355 
0-16 
/ 
9 
11. 
560,529 
0-16 
” 
14. 
596,790 
0-16 
The beam having undergone above half a million changes of load, by working con- 
tinuously for two months, night and day, at the rate of about eight changes per minute, 
without producing any visible alteration, the load was increased from one-fourth to two- 
sevenths of the statical breaking-weight, and the experiment proceeded with till the 
number of changes of load reached a million. 
2 x 
MDCCCLXIV. 
