CHAPTER IV.

He delivers a Course of Optical Lectures at Cambridge—Is elected Fellow of the Royal Society—He communicates to them his Discoveries on the different Refrangibility and Nature of Light— Popular Account of them—They involve him in various Controversies— His Dispute with Pardies—Linus—Lucas—Dr. Hooke and Mr. Huygens— The Influence of these Disputes on the mind of Newton 47