—- ss 
TRANSACTIONS OF THE SECTIONS. 203 
Mr. Fairbairn, who, with that liberality which I have experienced from 
him on former occasions, at once put every means of a full investiga- 
tion into my hands. He expressed a wish that I should extend the 
inquiry to pillars of various kinds, ancient as well as modern, and leave 
no part of the subject I undertook till I had obtained full satisfaction 
upon it from experiment. Thus freed from restraint, I endeavoured 
to forget the expense I put my friend to, in my wish to acquire the 
requisite information. 
The experiments are contained in thirteen tables, as below. 
Cast Iron. 
Table 1. Solid uniform cylindrical pillars, with rounded ends......... 55 
i 2s». Ditto ditto with flat ends ...,.....2+000. 51 
», 3. Solid uniform square pillars, with rounded ends,.........+- ssc ds 
» 4. Solid uniform cylindrical pillars, with discs............ssce0+es 12 
» 9% Ditto ditto with ends rounded, round- 23 
ed and flat, and both ends flat ...........cscsesceeeeeese. as 
» 6. Solid cylindrical pillars, enlarged middle, rounded ends...... 7 
yds Ditto ditto discs on ends ............ aca, ee 
» 8. Hollow uniform cylinders, rounded ends....:......2.2+++- seid = 
» 9. Hollow uniform cylinders, flat ends ..........sceceseecesessecees 
», 10. Short hollow uniform pillars, flat ends...........secseesscecseoes 
» 11. Pillars, hollow and solid, of various me. 2 and different 10 
modes of fixing...... eaenehaeasehs oppecscatas ee Ee iy 
Wrought Iron and Steel. 
», 12. Uniform cylindrical pillars of these metals ........... Seesecc -. 30 
Wood. 
», 13. Square pillars of oak, and other rectangular forms ........... apalltty 
259 
The pillars, during the experiments, were placed vertically, resting 
upon a flat, smooth plate of hardened steel, laid upon a cast-iron shelf, 
made very strong, and lying horizontal. The pressure was communi- 
cated to the upper end of the pillar by means of a strong lever acting 
upon a bolt of hardened steel, 25 inches diameter, and about a foot 
long, kept vertical by being made to pass through a hole bored in 
a deep mass of cast-iron; the hole being so turned as just to let the 
bolt slide easily through without lateral play. The top of the bolt was 
hemispherical, that the pressure from the lever might act through its 
axis; and the bottom was turned flat to rest upon the pillar. The 
bottom of this bolt, and the shelf on which the pillar stood, were 
necessarily kept parallel to each other; for the mass through which 
the bolt passed, and that on which the shelf rested, were parts of the 
same large case of iron, cast in one piece, and so formed as to admit 
shelves at various heights for breaking pillars of different lengths. 
The case had three of its four sides closed; circular apertures were, 
however, made through them, that the experimenter might observe the 
pillar without danger. 
