Royal Society. 167 



This paper may be viewed as a very important contribution to 

 organic chemistry, and as highly deserving of the Royal Medal ; an 

 award which will, doubtless, be hailed by chemists as a just encou- 

 ragement to perseverance in skilful analytical research. 



There being no paper on Mathematics coming within the stipu- 

 lations regulating the awards of the Royal Medals, which has been 

 deemed worthy of that for Mathematics in the present year, the 

 Council have, in virtue of the power given to them, under these cir- 

 cumstances, by the regulations prescribed by Her Majesty, awarded 

 the other Roy.nl Medal to Eaton Hodgkinson, Esq., for his paper, 

 which was published in the Philosophical Transactions for 1840, and 

 is entitled " Experimental Researches into the Strength of Pillars of 

 Cast Iron, and other materials." 



This paper has been esteemed by the Council to be peculiarly va- 

 luable in a practical as well as theoretical point of view, and there- 

 fore to deserve, in an eminent degree, the honour of a Royal Medal. 

 It contains the results of an immense series of experiments, conducted 

 M'ith great patience and admirable skill, and at a very considerable 

 cost. Mr. Hodgkinson's position among the manufactories of Man- 

 chester, together with the unlimited command over the resources of 

 one of the largest engineering establishments, which he obtained 

 through the liberality of its proprietor Mr. Fairbairn, enabled him 

 to direct his inquiries to the forms of pillars which are found most 

 useful in practice. The results of his labours he has reduced to em- 

 pirical formulae, peculiarly adapted for application to the purposes 

 of mechanical art. 



Among the most useful of the practical conclusions to which he 

 has arrived, the following are more particularly deserving of notice. 



Mr. Hodgkinson has found, that in all long pillars of the same di- 

 mensions, the resistance to crushing by flexure is about three times 

 greater when the ends of the pillars are flat, than when they are 

 rounded. A long uniform cast-iron pillar, with its ends firmly fixed, 

 whether by means of discs or otherwise, has the same power to re- 

 sist 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. The strength of a pillar with one end round and the other 

 flat, is the arithmetical mean between that of a pillar of the same 

 dimensions with both ends round, and one with both ends flat. Some 

 additional strength is given to a pillar by enlarging its diameter in 

 the middle part. 



The strength of long cast-iron pillars with relation to their dia- 

 meter and length is also made the subject of Mr. Hodgkinson's in- 

 vestigations ; and the rc!sult he deduces from them is, that the index 

 of the power of the diameter, to which the strength is proportional, 

 is S'l'M'i. He has also determined, by a comparison of experimental 

 results, the inverse power of the length to which the strength of the 

 pillar is proportional. The highest value of this power he finds to be 

 I'Ol I, till- lowest 1'.537, and the mean of all the comparisons 1'7I17. 

 lie thus deduces, first, approximate empirical foimulac for the break- 

 ing weight of solid pillars, and afterwards, more correct methods of 



