150 Royal Society :— 
the author shows the bearings of the facts educed on the action of 
affinity. 
The volume concludes with copious and most valuable tables for 
the calculation of analyses. 
To the chemist who is engaged in investigations of this nature, 
such a volume as that before us is invaluable; unhappily their 
number in this country is so limited, that we fear the work is likely 
to have a less-extended sale than it deserves, 
The translation has been entrusted to one of the author’s pupils, 
Dr. H. E. Roscoe, and it appears to be most carefully made. 
XVI. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
[Continued from p. 72.] 
January 8, 1857.—William Robert Grove, Esq., V.P., in the Chair. 
"Te following communications were read :— 
«Experimental Researches on the Strength of Pillars of Cast 
Tron.’ By Eaton Hodgkinson, Esq., F.R.S., Professor of the Mecha- 
nical Principles of Engineering, University College, London. 
In a previous paper on this subject (Philosophical Transactions, 
1840), I had shown,—lst, that a long circular pillar, with its 
ends flat, was about three times as strong as a pillar of the same 
length and diameter with its ends rounded in such a manner that the 
pressure would pass through the axis, the ends being made to turn 
easily, but not so small as to be crushed by the weight ; 2ndly, that 
if a pillar of the same length and diameter as the preceding had one 
end rounded and one flat, the strength would be twice as great as 
that of one with both ends rounded ; 3rdly, if, therefore, three pillars 
be taken, differing only in the form of their ends, the first having 
both ends rounded, the second one end rounded and one flat, 
and the third both ends flat, the strength of these pillars will be as 
1—2—3 nearly. 
The preceding properties having been arrived at experimentally, 
are here attempted to be demonstrated, at least approximately. 
The pillars referred to in my former paper were cast from Low 
Moor iron No. 3; they were very numerous, but usually much 
smaller than those used in the present trials, I felt desirous too of 
using the Low Moor iron in the hollow pillars employed on this 
occasion, not on account of its superior strength, but its other good 
qualities. The pillars from this iron were cast 10 feet long, and 
from 22 to 4 inches diameter, approaching in some degree, as to size, 
to the smaller ones used in practice. The results from the breaking 
weights of these were moderately consistent with the formule in the 
former paper, with a slight alteration of the constants, rendered 
necessary by the castings being of a larger size, and therefore softer 
than before, a matter which will be adverted to further on. 
The formule for the strength of a hollow pillar of Low Moor iron 
No. 2,—where w is the breaking weight, in tons, of a pillar whose 
