Opticks
Isaac Newton, 1704
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Newton reports a long series of experiments on light and colour. Using prisms, lenses and thin sheets of glass, he shows that sunlight is a mixture of rays that each bend by a different amount, and that colour belongs to how those rays are sensed and not to the rays themselves. The later books study thin films and the rings they make, and bending of light at edges. The work closes with a set of open questions about light, heat, gravity and method, which later readers treated as a guide for science.
Where it happens
- London Seat of the Royal Society, where Newton first reported his prism experiments in 1672; he spent his last decades here.13
- Cambridge Newton was admitted to Trinity College in 1661 and later held the Lucasian chair.3
- Woolsthorpe Manor Newton's birthplace in Lincolnshire,, where he later developed theories of calculus, optics and gravity.3
Through time
Who is in it, and behind it
Isaac Newton Author
English physicist and mathematician; his work on light was collected in Opticks, published in 1704.23
Robert Hooke Rival
His dispute with Newton over the corpuscular theory led Newton to delay publication until after Hooke's death in 1703.1
Christiaan Huygens Contemporary
His Treatise on Light is counted with Opticks among the major optics works of the Scientific Revolution; his wave theory was later supported by Young and Fresnel.1
Johannes Kepler Predecessor
His Astronomiae Pars Optica is one of the three major optics works of the period.1
Johann Wolfgang von Goethe Critic
Defended the older view of white light in his 1810 Theory of Colours.1
Voltaire Popularizer
Spread Newtonian science, including Opticks, in his 1738 book on Newton's philosophy.1
Thomas Young and Augustin-Jean Fresnel Later physicists
Showed the wave theory could account for colour as a matter of wavelength.1
What it is about
White light is a mixture
Light is made of different spectral hues, and all colours including white come from mixing them; this overturned the old view that white light is pure.1
Colour is a sensation
Each hue bends at its own angle, but colour is a sensation in the mind and not a property of objects or light itself.1
Experiment before hypothesis
The book is a record of experiments and their deductions, and each proposition is shown by a described test.1
Light as corpuscles
In the queries Newton guesses that light behaves like small particles, beyond what his experiments prove.1
Queries as open questions
Late queries range over heat, gravity, chemistry and ethics, mostly posed as rhetorical questions.1
In its own words
My Design in this Book is not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments:
For the Rays to speak properly are not coloured. In them there is nothing else than a certain Power and Disposition to[Pg 125] stir up a Sensation of this or that Colour.
Obs. 3. When the Rings or some parts of them appeared only black and white, they were very distinct and well defined, and the blackness seemed as intense as that of the central Spot.
This Explication of the Rain-bow is yet farther confirmed by the known Experiment (made by Antonius de Dominis and Des-Cartes ) of hanging up any where in the Sun-shine a Glass Globe filled with Water, and viewing it in such a posture, that the Rays which come from the Globe to the Eye may contain with the Sun's Rays an Angle of either 42 or 50 Degrees.
Query 1. Do not Bodies act upon Light at a distance, and by their action bend its Rays; and is not this action ( cæteris paribus ) strongest at the least distance?
Qu. 6. Do not black Bodies conceive heat more easily from Light than those of other Colours do, by[Pg 340] reason that the Light falling on them is not reflected outwards, but enters the Bodies, and is often reflected and refracted within them, until it be stifled and lost?
To tell us that every Species of Things is endow'd with an occult specifick Quality by which it acts and produces manifest Effects, is to tell us nothing:
The shape of the book
73 chapters, 100,541 words. Point at a bar.
How it came to be here
Opticks first appeared in English in 1704, without Newton's name on the title page, and a Latin version followed in 1706. He had reported the prism experiments to the Royal Society in 1672, but a bitter dispute with Robert Hooke led him to hold the book back until after Hooke died in 1703. Unlike the Principia, it is written in plain English and built from described experiments, not geometric proofs. The number of closing queries grew from sixteen in the first edition to 31 in the fourth edition of 1730.
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Sources
Text: PG 33504. US public domain (Project Gutenberg licence).