Published online by Cambridge University Press: 17 January 2013
By the discovery of the different refrangibility of light, Sir Isaac Newton laid open the true cause of the principal imperfection of refracting telescopes; and having inferred from the experiments which he made, that the refraction of the different rays composing the prismatic spectrum, was always in a given ratio to the refraction of the mean refrangible ray, this great philosopher was led to conclude, that the imperfection which he had discovered in dioptrical instruments was without remedy.
page 19 note * Philosophical Transactions of London, vol. 1. page 740.
page 20 note * This at least is true as to sense in those small refractions which take place in telescopes and microscopes; and it would be mathematically true in all cases, if the angles of incidence and refraction were proportional. But as it is not the angles themselves which are so, but their sines, it is a mistake to suppose that colourless refraction cannot be produced by large contrary refractions of the same medium, properly disposed for the purpose.
page 48 note * The cause, at that time unknown, was, that the solution happened to contain an unusual proportion of the marine acid; as will be understood from what follows.
page 53 note * From the Greek α privative, and the verb Πλανάω.
page 65 note * Philosophical Transactions of London, Vol. lxxix. p. 256.
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