Description of the improved achromatic telescope, London, late 18th century.
© Science Museum / Science & Society Picture Library
Printed Handbill giving a description of an improved achromatic telescope being sold by the English optical instrument makers Peter and George Dollond. John Dollond, the father of Peter developed the colour free achromatic double lens from an earlier idea during 1760s. In conjunction with his son Peter, John Dollond took a patent to protect his new design. This patent was succesfully defended several times against infringement from other London instrument makers.