NEWTON, ISAAC (b. Woolsthorpe, England, 25 December 1642; d. London, England, 20 March 1727), mathematics, dynamics, celestial mechanics, astronomy, optics, natural philosophy.

Revision of the “Opticks” (the Later Queries); Chemistry and Theory of Matter.

Newton's Opticks, published in 1704, concluded with a Third Book, consisting of eleven “Observations” and sixteen queries, occupying a bare five pages of print. A Latin translation, undertaken at Newton's behest by Samuel Clarke, appeared in 1706, and included as its most notable feature the expansion of the original sixteen queries into twenty-three. The new queries 17 through 23 correspond to the final queries 25-31 of the later editions. In a series of “Errata, Corrigenda, & Addenda,” at the beginning of the Latin volume, lengthy additions are provided to be inserted at the end of query 8 and of query 11; there is also a short insertion for query 14.

In a second English edition (London, 1717) the number of queries was increased to thirty-one. The queries appearing for the first time are numbered 17 to 24, and they have no counterparts in the 1706 Latin version. Newton's own copy of the 1717 English edition, in the Babson Institute Library, contains a number of emendations and corrections in Newton's hand, some of which were incorporated into the third edition (London 1721), as was a postscript to the end of the last sentence, referring to Noah and his sons.

The queries new to the 1717 edition cover a wide range of topics. Query 17 introduces the possibility that waves or vibrations may be excited in the eye by light and that vibrations of this sort may occur in the medium in which light travels. Query 18 suggests that radiant heat may be transmitted by vibrations of a medium subtler than air that pervades all bodies and expands by its elastic force throughout the heavenly spaces—the same medium by which light is put into “fits” of “easy” reflection and refraction, thus producing “Newton's rings.” In queries 19 and 20, variations in the density of this medium are given as the possible cause of refraction and of the “inflection” (diffraction) of light rays. Query 21 would have the medium be rarer within celestial bodies than in empty celestial spaces, which may “impel Bodies from the denser parts of the Medium towards the rarer”; its elasticity may be estimated by the ratio of the speed of light to the speed of sound. Although he referred in this query to the mutually repulsive “particles” of ether as being “exceedingly smaller than those of Air, or even those of Light,” Newton confessed that he does “not know what this Aether is.”

In query 22, the resistance of the ether is said to be inconsiderable; the exhalations emitted by “electrick” bodies and magnetic “effluvia” are offered as other instances of such rareness. The subject of vision is introduced in query 23. Here vision is again said to be chiefly the effect of vibrations of the medium, propagated through the “optick Nerves”; an analogy is made to hearing and the other senses. Animal motion (query 24) is considered as a result of vibrations in the medium propagated from the brain through the nerves to the muscles.

Queries 25 to 31 are the English recasting of queries 17 to 23 of the Latin edition. Query 25 contains a discussion of double refraction in calcite (Iceland spar) and a geometrical construction of both the ordinary ray and (fallaciously) the extraordinary ray; query 26 concludes that double refraction may be caused by the two “sides” of rays of light. Then, in query 27, Newton attacked as erroneous all hypotheses explaining optical phenomena by new modifications of rays, since such phenomena depend upon original unalterable properties.

Query 28 questions “all Hypotheses” in which light is supposed to be a “Pression or Motion, propagated through a fluid Medium.” Newton showed that Huygens' wave theory of double refraction would fail to account for the heating of bodies and the rectilinear propagation of light. Those who would fill “the Heavens with fluid Mediums” come under attack, while Newton praised the ancient philosophers who “made a Vacuum, and Atoms, and the Gravity of Atoms, the first Principles of their Philosophy.” He added that “the main Business of natural Philosophy is to argue from Phaenomena without feigning Hypotheses”; we are to “deduce Causes from Effects, till we come to the very first Cause, which certainly is not mechanical,” since nature exhibits design and purpose.

In query 29, Newton suggested that rays of light are composed of “very small Bodies emitted from shining Substances,” since rays could not have a permanent virtue in two of their sides (as demonstrated by the double refraction of Iceland spar) unless they be bodies. This query also contains Newton's famous theory that rays of light could be put into “Fits of easy Reflexion and easy Transmission” if they were “small Bodies which by their attractive Powers, or some other Force, stir up Vibrations in what they act upon.” These vibrations would move more swiftly than the rays themselves, would “overtake them successively,” and by agitating them “so as by turns to increase and decrease their Velocities” would put them into those “fits.”167 Newton further argued that if light were to consist of waves in an ethereal medium, then in order to have the fits of easy reflection and easy transmission, a second ether would be required, in which there would be waves (of higher velocity) to put the waves of the first ether into the necessary fits. He had, however, already argued in query 28 that it would be inconceivable for two ethers to be “diffused through all