GRAXTHAM ADDRESS. 277 



every branch of philosophy connected with it. Before 1601 

 he had not read Euclid ; in 1665 he had committed to writing 

 the method of Fluxions. At 25 years of age he had discovered 

 the law of gravitation, and laid the foundations of Celestial 

 Dynamics, the science created by him. Before ten years had 

 elapsed, he added to his discoveries that of the fundamental 

 properties of Light. So brilliant a course of discovery, in so 

 short a time changing and reconstructing Analytical, Astro- 

 nomical, and Optical science, almost defies belief. The state- 

 ment could only be deemed possible by an appeal to the 

 incontestable evidence that proves it strictly true.* 



By a rare felicity these doctrines gained the universal 

 assent of mankind as soon as they were clearly understood ; 

 and their originality has never been seriously called in ques- 

 tion. Some doubts having been raised respecting his inven- 

 ting the calculus, doubts raised in consequence of his so long 



* The birth of Newton was 25th Dec., 1642. (O. S.) or 5th Jan., 1643, 

 (N. S.) la 1661, 5th June, he was entered of Cambridge, and matricu- 

 lated 8th July. Before that tune he had applied himself in a desultory 

 way to parts of practical mechanics, as the movement of machines, and to 

 dialling. As soon as he arrived at Cambridge he began to read ' Euclid,' 

 and threw the book down as containing demonstrations of what he deemed 

 too manifest to require proof. It is, therefore, probable that he had before 

 meditated upon the position and proportion of lines, perhaps of angles. 

 Upon laying aside ' Euclid,' he took np ' Descartes' Geometry,' then 

 Kepler's Optics, which he speedily mastered, as he did a book on Logic, 

 showing the College Tutor that he had anticipated his lessons. In 1663 

 and '64 he worked upon Series and the Properties of Curves. In summer, 

 1664, he investigated the quadrature of the hyperbolic area by the Method 

 of Series which he had contrived. A paper in his handwriting dated 

 20th May, 1665, gives the method of Fluxions, and its application to the 

 finding of tangents, and the radius of curvature. So that at tlu's time the 

 direct method at least was invented. Another paper also in his hand- 

 writing, Oct., 1666, gives its application to equations involving surds. 



The Optical Lectures in 1669, 70 and '71, give the doctrine of Different 

 Refrangibility. In 1665 he formed the opinion of gravitation extending 

 to the heavenly bodies, but was prevented from drawing the conclusion 

 definitively, by the imperfect estimate of a degree as 60 miles, to which 

 alone he had access. After 1670, when Picard showed it to be 69 miles 

 he resumed his demonstration, and found it exact. 



