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The life of Sir Isaac Newton / By David Brewster.

David Brewster

Date:: 1831

Credit: The life of Sir Isaac Newton / By David Brewster. Source: Wellcome Collection.

119/392 page 97

$Te) x CHAPTER VIII. Newton's Discoveries respecting the Inflexion or Diffraction of Light—Previous discoveries of Grimaldi and Dr Hooke —Labours of succeeding Philosophers—Law of interference of Dr Young—Fresnel's Discoveries—New Theory of In- flexion on the hypothesis of the Materiality of Light. ALTHOUGH the discoveries of Newton respecting the Inflexion of Light were first published in his Opticks in 1704, yet there is reason to think that they were made at a much earlier period. Sir Isaac, indeed, informs us, in his preface to that great work, that the third book, which contains these discoveries, “ was put together out of scattered pa- pers ;’ and he adds at the end of his observations, that “he designed to repeat most of them with more care and exactness, and to make some new ones for determining the manner how the rays of light are bent in their passage by bodies, for mak- ing the fringes of colours with the dark lines be- tween them. But I was then interrupted, and cannot now think of taking these things into con- sideration.” On the 18th March 1674, Dr Hooke had read a valuable memoir on the phenomena of diffraction ; and, as Sir Isaac makes no allusion what- ever to this work, it is the more probable that his G$

The life of Sir Isaac Newton / By David Brewster.

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