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rash unwarranted generalization. I have the less hesitation' in using 

 Professor Tait's book, because many years ago I examined him for his 

 degree, and I remember that early in the examination his remarkable 

 powers caught my attention, and I was confident that we had got the 

 right man in the right place when we placed him as Senior Wrangler. 

 Under these circumstances, you will, I am sure, admit that any theft on 

 my part from the Professor's Lectures may be described as justifiable 

 appropriation. 



I \vish then to direct your attention to two or three great advances 

 which have been lately made in our scientific knowledge — advances 

 which have a special interest, as bearing upon the general question of 

 the structure of the physical universe. 



Towards the knowledge of this structure we have been making 

 steady progress for many years. The establishment of the Copemican 

 theory was one great step : the discovery of Kepler's laws of planetary 

 motion has been another : the theory of universal gravitation applied by 

 Newton to explain the mechanical motion of the heavenly bodies, and 

 the more complete development of the results of the theory by Laplace, 

 Lagrange, and other masters in mathematical science has been a still 

 further and a quite gigantic step. These and the like theoretical investi- 

 gations, combined with almost unmeasured improvements in methods of 

 observation, have advanced physical astronomy to an exceedingly high 

 scientific pre-eminence, and one from which it may be safely asserted 

 that it can never again be dislodged. Then, on the other hand, such 

 discoveries as that by Dalton of the combination of the atoms of 

 matter according to definite numerical proportions, and the investigations 

 made through the microscope of small objects close at hand, corres- 

 ponding to the investigations made through the telescope of distant 

 bodies, have established another branch of physical science upon 

 foundations hardly less secure than those upon which physical astronomy 

 itself rests. Had our knowledge of the material universe been found 

 incapable of advancement beyond the point which it had reached, say, 

 forty years ago, the results would still have been splendid and absolutely 

 marvellous to contemplate. 



