450 WILHELM EDUARD WEBER. 



at Leipzig, but he returned to his former position in Gottiugen in 

 1849. 



The chief contributions to science, those for which he is now best 

 known, and will long continue to be known, are, first, a series of papers 

 beginning in 1846, and continued at intervals to 1864, in which he 

 for the first time showed how the principles of absolute measurement 

 which Gauss had applied to magnetism were applicable to electricity. 

 Until Weber's work there had been no such thing as electrical 

 measurements. There had been nothing more than comparisons 

 between magnitudes of the same kind. Weber showed how an elec- 

 trical quantity could be stated in terms of the unit of time, length, 

 and mass, without any reference to other electrical phenomena, and 

 this was a new and great achievement. The British Association Com- 

 mittee on Electrical Standards adopted Weber's work as a basis for 

 their standards of units. 



Secondly, he was one of the first to feel the necessity for an adequate 

 mechanical conception of electro-magnetic phenomena, and he worked 

 out in a mathematical way, and gave consistency to the idea of mo- 

 lecular magnets, that is, that every molecule of iron is a magnet by 

 constitution, and the various phenomena of the magnetic field are due 

 to the relative positions of these molecules. It hardly needs to be 

 said, that all the known phenomena of magnets, up to date, tend to 

 corroborate and strengthen that conception. 



He was an honorary member of many of the learned societies of 

 Europe, as well as of the American Academy. 



He died on June 23, 1891, and was therefore eighty-seven years 

 of age. 



The names of five persons have been dropped from the list 

 of Resident Fellows on account of removal from the Com- 

 monwealth or non-payment of assessments. 



The Academy has received an accession of ten Resident 

 Fellows, and two Associate Fellows. 



The Roll of the Academy, corrected to date, includes the 

 names of 176 Fellows, 87 Associate Fellows, and 65 Foreign 

 Honorary Members. 



May 24, 1892. 



