204 MEMOIR OF EATON HODGKINSON. 



For the first paper the council of the Royal Society awarded the gold medal 

 as a mark of their a2:)preciation of its practical investigations. 



He was appointed professor of the mechanical principles of engineering at 

 TJniversit}^ College, London, on the 6th of Februar}^, 1847, and lectured during 

 the sessions of 1847 to 1853, inclusive. In 1847 he was appointed a member of 

 the royal commission to inquire into the properties of wrought and cast iron and 

 their application to railway structm'es. The results of his labors in this impor- 

 tant inquiry are given, with marked reference to their magnitude and efficiency, in 

 the commissioners' report of 1849. He was consulted by the late Robert Stephen- 

 son in reference to the construction of that great national work, the tubular bridge 

 over the Menai straits. His experience and mathematical knowledge enabled 

 him to suggest and carry out a series of experiments, at the cost of several 

 thousand pounds, with a view to investigate the bearing properties of wrought 

 iron rivited tubes, and to satisfy the mind of this great engineer as to the sta- 

 bility and safety of the Britannia and Conway tubular bridges. He edited an 

 edition of " Tredgold on Cast Iron," to which he added a second volume, giving 

 an account of his own experiments and discoveries, published b}' Weale, 1846. 

 The title of the second volume is, " Experimental Researches on the Strength 

 and other Properties of Cast Iron, with the development of New Principles, calcu- 

 lations deduced from them, and inquiries applicable to Rigid and Tenacious Bodies 

 generally." 



The most novel and important conclusions here given are as follows : 



Tlie strengths of long pillars of cast iron, wrought iron, cast steel, and 

 Dantzic oak, of the same dimensions, are in proportion to the numbers 1,000, 

 1,745, 2,518, 109. Cast iron is not reduced in strength when its temperature is 

 raised to 600°. 



The sets, in cast-iron beams, vary nearly as the square of the force of deflec- 

 tion ; hence any force, however small, will injure the elasticity of cast iron. 

 The strength in tons of beams approaching the best form is measured by the 

 formula 2.166ad-^], where a= area of section of bottom flange in the middle, 

 d= the depth in inches of the beam, and Z= the distance in feet. 



A general investigation of the position of the neutral line is given on the 

 principle that the forces of extension and compression of a particle vary as any 

 function of its distance from the neutral line. This includes every hypothesis 

 which has been proposed in order to compute the strength of material bodies 

 subjected to strains. 



BIETH A^B EDUCATION. 



As I have already stated, Mr. Hodgkinson was born at Anderton, Cheshire, 

 in the year 1789. His father, a respectable farmer, died of fever when his son 

 Eaton was about six years of age, leaving Mrs. Hodgkinson with two daughters 

 and a son. On liis fatlier's decease his raotlier determined to continue the farm ; and 

 by industry, thriftiness, and business-like habits she was enabled to educate her 

 children respectably, and to send her son to the Grammar School of Northwich. 

 At this school he received the rudiments of a classical education, as he studied 

 the Latin, Greek, and Hebrew languages under the immediate supervision of 

 the head master, Mr. Littler. This was done to meet the wish of his uncle, the 

 Rev. Henry Hodgkinson, rector of Aberfield, Berkshire, who was ver^'- anxious 

 that his nephew should be educated with a view of going to Oxford or Cam- 

 bridge, to prepare for the church. The desire of his uncle was, for a time, grati- 

 fied, and the hope was strongl}- indulged that one day Eaton Hodgkinson would 

 be a student of one of the universities ; hence the study of classics in his early 

 youth was considered indispensable, although it was not exactly in conformity 

 with his tastes and habits of thought, as at an early age he was naturally more 

 inclined to the study of mathematics than of languages. 



