Sir Isaac Newton's own drawing of his reflecting telescope. Newton designed and built the first reflecting telescope in 1668. The telescope worked by focusing light by reflection from a parabolic mirror, instead of by refraction through a lens. The design avoided the chromatic aberration and loss of light caused by the use of lenses and was highly successful; the largest modern telescopes are all of the reflecting variety. Newton's first telescope was only 15 cm long & 2.5 cm in diameter but could magnify 30-40 times. He built a second larger version, probably the one shown here, in 1671.