188 Josiah Willard Gihhs. 



speaking of liis unfinished translation of Gesenius's Hebrew 

 Lexicon : " But with his wonted thoroughness, he could not 

 leave a word until he had made the article upon it perfect, 

 sifting what the author had written by independent investiga- 

 tions of his own." 



His son entered Yale College in 1854 and was graduated in 

 1858, receiving during his college course several prizes for 

 excellence in Latin and Mathematics ; during the next five 

 years he continued his studies in New Haven, and in 1863 

 received the degree of doctor of philosophy and was appointed 

 a tutor in the college for a term of three years. During the 

 first two years of his tutorship he taught Latin and in the third 

 year Natural Philosophy, in both of which subjects he had 

 gained marked distinction as an undergraduate. At the end 

 of his term as tutor he went abroad with his sisters, spending 

 the winter of 1866-67 in Paris and the following year in Ber- 

 lin, where he heard the lectures of Magnus and other teachers 

 of physics and of mathematics. In 1868 he went to Heidel- 

 berg, where Kirchhoff and Helmholtz were then stationed, 

 returning to New Haven in June, 1869. Two years later he 

 was appointed Professor of Mathematical Physics in Yale Col- 

 lege, a position which he held until the time of his death. 



It was not until 1873, when he was thirty-four years old, 

 that he gave to the world, by publication, evidence of his 

 extraordinary powers as an investigator in mathematical physics. 

 In that year two papers appeared in the Transactions of the 

 Connecticut Academy, the first being entitled " Graphical 

 Methods in the Thermodynamics of Fluids," and the second 

 " A Method of Geometrical Representation of the Thermody- 

 namic Properties of Substances by Means of Surfaces." These 

 were followed in 1876 and 1878 by the two parts of the great 

 paper " On the Equilibrium of Heterogeneous Substances," 

 which is generally, and probably rightly, considered his most 

 important contribution to physical science, and which is unques- 

 tionably among the greatest and most enduring monuments 

 of the wonderful scientific activity of the nineteenth century. 

 The first two papers of this series, although somewhat over- 

 shadowed by the third, are themselves very remarkable and 

 valuable contributions to the theory of thermodynamics ; they 

 have proved useful and fertile in many direct ways and, in 

 addition, it is diflScult to see how, without them, the third could 

 have been written. In logical development the three are very 

 closely connected, and methods first brought forward in the 

 earlier papers are used continually in the third. 



Professor Gibbs was much inclined to the use of geometri- 

 cal illustrations, which he employed as symbols and aids to the 

 imagination, rather than the mechanical models which have 



