208 MEMOIR OF EATON HODGKINSON. 



bis papers, "with a view to publish them, so that they might be more accessible 

 to engineers than they now are in the volmnes of learned societies. 



Mr. Hodgkinson's religious emotions were silent, devotional in the highest 

 sense — not sectarian ; they were strictly confined to the channel between his 

 Maker and his own soul. And in this way they were purified by the truth from 

 heaven, bearing the precious fruit of meekness, charity, and implicit confidence 

 in Him who is all and sustains all. His religion was the arbiter of his life, the 

 judge of the many and important obligations between God, his fellow-man, and 

 himself. His end was peaceful, and he has left a name marked by strict integ- 

 rity, which will be well remembered in the walks of science for ages yet to 

 come. 



Let us now pass on to notice more in detail the works of Mr. Hodgkinson, 

 which have raised him to a good degree among his contemporaries, and Avill also 

 be the introduction to future thinkers in the same field of labor which he suc- 

 cessfully cultivated. 



''On\he Transverse Strain and Strength of Metals," (read March 22, 1822.) 



The objects aimed at in this paper are, as stated by the author, to unite, in a 

 general formula, the commonly received theories in which all the fibres are con- 

 ceived to be in a state of tension ; and next, to adapt the investigation to the 

 more general case, where part of the fibres are extended and part compressed, 

 and to seek experimentall}'^ for the laws that regulate both the extensions and 

 compressions. The manner in which these objects have been sought and devel- 

 oped is a model worthy of every commendation, of clear, sound, geometrical 

 reasoning and refined artifice. And the data necessary to give practical effect 

 to the various analytical formulae have been obtained from experiments, than 

 which none have been recorded with greater fidelity and less contortion to meet 

 the demands of particular theories. No painstaking or expense was considered 

 too great to make the results of the experiments successful and trustworthy^, so 

 that the engineer and philosopher alike could place implicit reliance upon them. 

 In these experiments there is recorded, for the first time, an element which has 

 furnished a theme for many animated discussions of late years among philoso- 

 phers and practical engineers, and which became an important object of research 

 in all Mr. Hodgkinson's subsequent experiments, viz., set, or the difference 

 between the original position of a strained body and the position which it assumes 

 when the strain is removed. 



Tins point, which is full of interest and important consequences to the prac- 

 tical man, cannot now be discussed. On examination I believe that I shall be 

 borne out in the statement that, notwithstanding the number of books which have 

 been written during the last 30 years on the strength and strain of materials, 

 some of a more ambitious kind, and others having the humbler object of Vjeing 

 useful in communicating information to the artisan, still there is none from which 

 a clearer and more satisfactory exposition of this subject can be gathered than 

 from the paper above referred to by Mr. Hodgkinson, in the volume for 1822. 

 The Tuscan philosopher, Galileo, has the merit of first propounding a theory of 

 the strength of materials, and applying the unerring principles of geometry to 

 the computation of the strength of beams of given dimensions. With Leibnitz 

 oiiginated the idea of the force of extension of a fibre being proportional to its 

 distance from the lower side of a bent beam. James Bernoulli first suggested 

 the notion (for it never assumed any other shape in his mind) of a nattntl li)ic 

 in the section of rupture. But to the late Professor Hodgkinson belonged ,the 

 merit of giving practical effect, in this paper, to the happy suggestion of Ber- 

 noulli, by showing, both theoretically and experimentally, the true method of 

 determining, in the section of fracture, the exact position of the neutral line, and 

 of calculating the strength of the beam. 



In order, then, to show more clearly the steps taken by Mr. Hodgkinson in 



