418 
MR. HODGKINSON’S EXPERIMENTAL RESEARCHES 
Mr. Fairbairn intends that the results of these experiments shall continue to be 
observed in conjunction with his interesting experiments upon the effect of long-con- 
tinued pressure upon horizontal bars. 
The results obtained up to the present time are below, as taken from Mr. Fairbairn’s 
register. 
Uniform pillars of Low Moor Iron, No. 3, each six feet long and one inch diameter, 
rounded at the ends, and placed vertical with the following weights on each. 
Date of obser- 
vation. 
Tempera- 
ture Fahr. 
1st Experiment. 
Weight of pillar 
14 lbs. 13 oz. 
Permanent load 
448 lbs. 
2nd Experiment. 
Weight of pillar 
14 lbs. 13 oz. 
Permanent load 
784 lbs. 
3rd Experiment. 
Weight of pillar 
14 lbs. 11 oz. 
Permanent load 
1120 lbs. 
4th Experiment. 
Weight of pillar 
14 lbs. 13 oz. 
Permanent load 
1456 lbs. 
Deflections. 
Deflections. 
Deflections. 
Deflections. 
1839. 
inch. 
inch. 
inch. 
inch. 
July 5. 
72 
•018 
•03 
6. 
68 
•215 
•250 
8. 
69 
•01 
•02 
•230 
•275 
16. 
63 
•01 
•023 
•235 
•310 
23. 
64 
•01 
•02 
•235 
•320 
Aug. 15. 
63 
•01 
•023 
•235 
•395 
Nov. 7- 
50 
•01 
•03 
•24 
•825 
Dec. 9* 
39 
•01 
•025 
•243 
•955 
1840. 
f Broke about 19 th 
Feb. 14. 
50 
•01 
•025 
•245 
< or 20th Decern- 
[ her, 1839- 
April 27 *. 
63 
•01 
•025 
•365 
June 6. 
61 
•01 
•025 
•380 
Aug. 3. 
74 
•01 
•030 
•395 
Sept. 14. 
55 
•01 
•025 
•380 
A pillar of the same dimensions, and cast at the same time as those above, was 
broken with 1500 lbs. laid gradually upon it. Hence, supposing the strengths to be 
1456 9 j 
the same, we see that the pillar in the fourth experiment above, had borne y^, or loo 
of its breaking weight, between five and six months ; though the deflection had been 
regularly increasing from the first. I would therefore infer, that the short or long 
time employed in making an experiment has little influence upon its result. 
In concluding my inquiries into the strength of cast-iron pillars, I shall give the 
tensile, compressive, and transverse strengths, together with the specific gravity of 
the iron made use of, to serve as data for other researches. 
Tensile Strength of Low Moor Iron, No. 3, or resistance which it would offer to a direct 
force tending to tear it asunder. 
54. The castings were of the same form as were used for this purpose in my Report 
on the Strength of Cast Iron-j'-. The form of the section torn asunder was —|— ; and 
the force was in a line perpendicular to this, and passing through the centre. The 
* The experiments of this and the subsequent dates were inserted during the printing of the paper, 
t Transactions of the British Association, vol. vi. 
