xiv JOSIAH WILLARD GIBBS. 



father's side we find an unbroken line of six college graduates. Five 

 of these were graduates of Harvard, President Samuel Willard, his 

 son Josiah Willard, the great grandfather, grandfather and father of 

 the elder Professor Gibbs, who was himself a graduate of Yale. 

 Among his mother's ancestors were two more Yale graduates, one of 

 whom, Rev. Jonathan Dickinson, was the first President of the College 

 of New Jersey. 



Josiah Willard Gibbs, the younger, 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 Berlin, 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 College, 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 Thermodynamic 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 contri- 

 bution to physical science, and which is unquestionably 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 overshadowed by the third, are themselves very 

 remarkable and valuable contributions to the theory of thermo- 

 dynamics ; they have proved useful and fertile in many direct ways, 

 and, in addition, it is difficult 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 geometrical 



