MEMOIR OF THE LATE PROF. E. HODGKINSON, F.R.S. 185 



iron, to increase the resistance of the top to a crushing 

 force. 



These are important practical problems ; and when the 

 issue is considered, viz. the continued stability of the Con- 

 way and Britannia Tubular Bridges, they required for their 

 solution great skill in the subtilties and artifices of ma- 

 thematical and experimental science. The answers which 

 Mr. Hodgkinson obtained to the above problems were 

 deemed by Mr. Stephenson to be so satisfactory as to en- 

 able him with confidence to build the Tubular Bridges. 



A concise but clear exposition of these answers is given 

 by Mr. E. Clark before the Commissioners appointed to 

 inquire into the application of iron to railway purposes 

 (see Report, page 359). 



It was impossible that such assistance in the execution 

 of a novel design could be lightly esteemed or inadequately 

 appreciated by the great engineer. Hence, in the history 

 of these tubular bridges, where Mr. Stephenson is anxious 

 to record the merits of his assistants, he frankly acknow- 

 ledges his deep obligations to the mathematical philosopher 

 "/or devising and carrying out a series of experiments 

 v)Jiich terminated in establishing the laws that regulate the 

 strength of tubular structures j in a manner so satisfactory 

 that I was enabled to proceed with more confidence than I 

 otherwise should have done '^ (see vol. i. p. 35, of the 

 ^Britannia and Conway Tubular Bridges,^ by E. Clark, 

 Esq.). 



This declaration of Mr. Stephenson completely disarms 

 all future praise or detraction with respect to the part which 

 Mr. Hodgkinson took in the execution of the tubular 

 bridges. It places him before the public in his right posi- 

 tion as a most important contributor to the success of an 

 enterprise which will represent the engineering skill of the 

 present time, and will be the admiration of future ages. 

 E. Clark, Esq., who superintended the building of the 



