Newton's first reflecting telescope, 1668.
© Science Museum / Science & Society Picture Library
This is a replica of the first reflecting telescope made by Sir Isaac Newton (1642-1727) and shown to the Royal Society in 1668. Newton's telescope uses a concave mirror to gather light, instead of a simple lens which produces false colour due to the dispersion of light. To use the telescope, the viewer looks through an eyepiece on the side of the tube. The light path is reflected off both the primary mirror and a flat secondary one at the entrance to the tube near the top. Made in 1924 by F L Agate, this is a faithful copy of the original that still resides with the Royal Society after more than three hundred years.