114 Mr Fairbairn on Fireproof Warehouses. 
diameter, and half the length, with ends rounded, was nearly 
alike. 
The conclusion, as Mr Hodgkinson observes, is, therefore, 
“ that a long uniform cast-iron pillar, with its ends firmly 
fixed (whether by means of discs or otherwise), has the same 
power to resist breaking as a pillar of the same diameter and 
half the length, with the ends rounded, or turned, so that the 
force would pass through the axis.” 
Mr Hodgkinson, in the first experiments, gave the strength 
of cast-iron pillars, with both their ends rounded, and both 
flat ; subsequently he experimented upon those with one end 
rounded and the other flat, and in some cases with dises, 
and their results being placed between those from the pillars, 
with round and flat ends, gave the strength in a constant 
ratio, as under :-— 
Pillars. Breaking Weight in Ibs, 
Both ends rounded, . . | 143 | 3017 7009 7009 | 16493 
Oneend roundedandoneflat,, 256 | 6278 | 13499 | 13565 | 13557 
Both ends flat,. . . . 487 | 9007 | 20310 | 22475 | —— 
« The pillars in each vertical column in this abstract are 
of the same length and diameter ; the strengths, therefore, 
in three different cases, reading downwards, are as 1, 2, 3 
nearly, the middle being in arithmetical mean between the 
other two.” 
Mr Hodgkinson, therefore, found, by other experiments 
upon timber, wrought iron, steel, &c., that those, as well as 
every other sort and description of material, followed (as re- 
gards their strengths) the same laws, and that the strength 
of a pillar with one end round and the other flat is always 
an arithmetical mean between the strength of pillars of the 
same dimensions with both ends rounded and both flat. 
These are facts which should on no account be mistaken 
in the construction of fireproof buildings ; and it will be well 
