ADDRESS OF SIR WILLIAM HAMILTON. li 
which their constituent elements are arranged and held together. 
Various departments of science appear to be connected together by 
the relation they have to this problem. The theories of light, heat, 
electricity, chemistry, mineralogy, crystallography, all bear upon it. 
A review, therefore, of the solutions that have been proposed of all 
such questions as cannot be handled without some hypotheses respect¬ 
ing the physical condition of the constituent elements of bodies, would 
probably conduce by a comparison of the hypotheses towards reaching 
that generalization to which the known connexion of the sciences seems 
to point.” The author finally remarks, that “ questions of this kind 
have of late largely engaged the attention of some French mathemati¬ 
cians, and the nature of their theories, and the results of the calcula¬ 
tions founded on them, deserve to be brought as much as possible into 
notice.” Acting upon these just views, Mr. Challis has accordingly 
performed, for the British Association and for the British public, the 
important office of reviewing and reporting upon those researches of 
Laplace, Poisson, and Gauss, respecting the connexion of molecular 
attraction, and of the repulsion of heat, with the ascent of fluids in 
tubes, which give to his report so much of that foreign character which 
I have already ventured to ascribe to it; yet, it is just to add, and, 
indeed, Mr. Challis does so, that as Newton first resolved the ma¬ 
thematical problem of gravitation, in its bearings on the motion of a 
planet about the sun, and went far to resolve the same extensive pro¬ 
blem in its details of perturbation also ; he likewise first resolved a 
problem of molecular forces, and clearly foresaw and foretold the ex¬ 
tensive and almost universal application of such forces to the mathe¬ 
matical explanation of the most varied classes of phsenomena; and that 
the theory of capillary attraction, in particular, has received some very 
valuable illustrations in England from the late Dr. Thomas Young. I 
ought to mention that a very interesting report, on the foreign mathe¬ 
matical theories of electricity and magnetism was read in part this 
morning to the mathematical and physical section, by the Rev. Mr. 
Whewell. 
The next report after that of Mr. Challis in the volume, is the re¬ 
port I have already alluded to, by Professor Lloyd, on the progress and 
present state of physical optics; respecting which 1 should have much 
to say, if I did not fear to offend the modesty of the author, and were 
not restrained by the recollection that he is a member of the same Uni¬ 
versity with myself, and a countryman and friend of my own. I shall 
therefore simply express my belief, that no person who shall hereafter 
set about to form an opinion of his own on the question between the 
two theories of light, will think himself at liberty to dispense with the 
