THE BELFAST ADDRESS. 161 



to feel the ethic glow with which his lecture concludes, 

 There is, moreover, a very noble strain of eloquence 

 in his description of the steadfastness of the atoms : 

 * Natural causes, as we know, are at work, which tend 

 to modify, if they do not at length destroy, all the 

 arrangements and dimensions of the earth and the 

 whole solar system. But though in the course of ages 

 catastrophes have occurred and may yet occur in the 

 heavens, though ancient systems may be dissolved and 

 new systems evolved out of their ruins, the molecules 

 out of which these systems are built the foundation 

 stones of the material universe remain unbroken and 

 unworn.' 



The atomic doctrine, in whole or in part, was enter- 

 tained by Bacon, Descartes, Hobbes, Locke,' Newton, 

 Boyle, and their successors, until the chemical la\\ of 

 multiple proportions enabled Dalton to confer upon it 

 an entirely new significance. In our day there are 

 secessions from the theory, but it still stands firm. 

 Loschmidt, Stoney, and Sir William Thomson have 

 sought to determine the sizes of the atoms, or rather to 

 fix the limits between which their sizes lie ; while the 

 discourses of Williamson and Maxwell delivered in 

 Bradford in 1873 illustrate the present hold of the 

 doctrine upon the foremost scientific minds. In fact, 

 it may be doubted whether, wanting this fundamental 

 conception, a theory of the material universe is capable 

 of scientific statement. 



5. 



Ninety years subsequent to Grassendi the doctrine 

 of bodily instruments, as it may be called, assumed 

 immense importance in the hands of Bishop Butler, 

 who, in his famous ' Analogy of Keligion,' developed, 

 from his own point of view, and with consummate 



