Isaac Newton (1642 - 1727)

Sir Isaac Newton (Figure 1), scientist, theologian and administrator lived over three centuries ago; but ever since his death at the age of eighty-five in 1727 his eminence has been unquestioned. His younger contemporary, Alexandra Pope, went so far as to write:

'Nature and Nature's laws lay hid in night: God said, "Let Newton be!" And all was light.'

Figure 1 (left). Sir Isaac Newton.

Newton was an outstanding physicist and amongst many accomplishments is recognized for proving that 'white light' was actually composed of a 'spectrum' of colours. Newton's treatise on the reflection, refraction and colours of light - 'Opticks' (Figure 2) - published in 1704, stands to this day unchallenged (although interestingly he had for many years avoided publishing his ideas because of stern criticism from his peers). Intrigued by the appearance of colours in images from 'imperfectly' ground lenses Newton set about investigating the cause. He cut a slit in a window blind of a darkened room and set up a prism such that it would intercept the shaft of sunlight from the slit (Figure 3). A bright patch of colours appeared, ranging from deep red at one end to blue, indigo and violet at the other. He then introduced a second prism in different configurations, to prove that each colour was pure and could not be further 'separated' and also that the whole colour spectrum could be 're-combined' into white sunlight again. Although Newton was not aware of radiations beyond the red and violet he certainly carries the recognition for having discovered the 'spectrum.'

Figure 2 (left). Isaac Newton's 'Opticks'.

Figure 3 (above). Sunlight split through a prism.