ON THE STEENOTH OE PILLAES OF CAST lEON. 
893 
Appendix. 
The following experiments were made after the others had been offered to the Royal 
Society, or during the months of October and November 1857, and as the former solid 
pillars were from various parts of the kingdom, and usually of the iron termed No. 1, 
I was desirous of adding the results from a few solid pillars of the quality No. 2. These 
latter pillars were mostly cast circular, and were made 10 feet long and 2 ^ inches 
diameter, with then- ends turned flat as before. To these were added pillars of nearly 
the same weight, of a square and a triangular form of section, to ascertain the compa- 
rative strength of pillars whose sections were circular, square, and triangular. 
The cylindrical pillars, in the experiments of which an abstract is given below, though 
of different irons, were all cast from the same model ; and the square and the triangular 
pillars were of the same kind of iron as two of the circular ones (the Calder, No. 2), 
and were intended to be of the same weights as these. All the pillars were made 
imiform throughout their lengths, 10 feet long each, and turned flat at the ends. 
As the weights of the different pillars did not differ widely from 150 lbs. each, the 
breaking weight of each is reduced to what it would have been if the weight had 
been 150 lbs. 
The reduced results are as below. 
Pillars broken. 
Second quality of iron, or that 
of No. 2. 
Assumed weight 
of Pillars. 
Breaking weights and 
forms of section. 
lbs. 
lbs. 
1st pillar 
Coltness Iron, No. 2 
150 
050328 
2nd pillar 
Old Park Iron, No. 2 
150 
054736 
3rd pillar 
Blaenavon Iron, No. 2 
150 
0 55611 
4 th pillar 
Calder Iron, No. 2 
150 
556581 Mean. 
O >55299 lbs. 
5th pillar 
Calder Iron, second specimen 
150 
54940 J 
6th pillar 
Calder Iron, No. 2 
150 
491851 
n >51537 lbs. 
7th pillar 
Calder Iron, second specimen 
150 
53890 J 
8 th pillar 
Calder Iron, No. 2 
150 
57332q 
^ )>6l0561bs. 
9 th pillar 
Calder Iron, second specimen 
150 
64780 J 
From the three last mean results it appears that the strengths of circular, square, and 
triangular solid pillars of the same quality, weight and length, vary as 55299, 51537, 
and 61056, the last being the strongest. This last conclusion, respecting the strength 
of triangular solid pillars, may not be considered void of importance. See Notes to 
experiments 8 and 9, Table IX. following. 
Whence it appears that solid triangular pillars with flat ends are stronger than those 
with either circular or square sections ; but this seems not to be the case in pillars with 
rounded ends, for from my former experiments*, a pillar, whose section is +, as in the 
connecting rod of a steam-engine, the ends being moveable, is very weak to bear a strain 
* Philosophical Transactions, 1840, pages 413 and 455. 
6 A 
MDCCCLVII. 
