20 The Period from 1871 to 1880 



IV. THE PERIOD FROM 1871 TO 1880 



On the whole, the decade under consideration was one in which the im- 

 plications of previous theories were being tested by observation and experi- 

 ment. Astronomers were making spectroscopic observations of the sun; 

 physicists were investigating the consequences of the relations between elec- 

 tric currents and magnetism ; chemists were rapidly developing analytic 

 chemistry and discovering new elements ; geologists were reading the strata 

 of the rocks in the light of the uniformitarian theory as expounded by Lyell 

 (1836-35) ; and biologists were coming to realize the profound significance 

 of Darwin's Origin of Species (1859). It was a period in which many 

 scientists, with the enthusiasm of pioneers, were entering and exploring vast 

 regions the masters had opened. 



Theoretical chemistry received a great impetus during this period by the 

 publication just before its beginning of Mendeleeff's periodic table of the 

 chemical elements. An equally great contribution to chemistry and physical 

 science was the publication, in 1877, of J. Willard Gibb's paper "On the 

 Equilibrium of Heterogeneous Solution," a profound work which was not 

 generally understood or appreciated for many years. On the other hand, 

 Maxwell's electromagnetic theory (1873) was almost immediately accepted. 



Presidential Addresses 



William Chauvenet (mathematician), who was elected president of the 

 Association for 1870, died early in the year and was succeeded by T. Sterry 

 Hunt, vice-president of the Association. Hunt (geologist) delivered his 

 address as retiring president at the meeting held in Indianapolis, Ind., in 

 August, 1 87 1. Instead of delivering a general philosophical discussion on 

 science and the role the Association might play in its advancement, as many 

 of his predecessors had done, he limited himself to his own field, the funda- 

 mental problems relating to the crystalline stratified rocks in the north- 

 eastern part of the United States. After describing the rocks that are ex- 

 posed in the region, he entered into a lengthy discussion of their origin, opin- 

 ions concerning which were rapidly changing at the time. He closed his 

 address as follows (vol. 20, pp. 1-59) : 



