Alhazen's problem
                                Date
                            
                            
                                26 June 1669
                            
                            
                        
                            
                            
                            
                                Creator
                            
                            
                                Unknown, Artist
                            
                            
                        
                            
                            
                            
                                Object type
                            
                            
                            
                        
                            
                            
                            
                                Archive reference number
                            
                            
                            
                        
                            
                            
                            
                                Manuscript page number
                            
                            
                                p1
                            
                            
                        
                            
                            
                            
                                Material
                            
                            
                            
                        
                            
                            
                            
                                Dimensions
                            
                            
                                height (page): 205mm
width (page): 160mm
                            
                        
                            
                            
                            width (page): 160mm
                                Subject
                            
                            
                            
                        
                            
                            
                            
                                Description
                            
                            
                                This is a figure relating to Christian Huygens's treatment of Alhazen's problem, which was enclosed with his letter to Henry Oldenburg dated 26 June 1669. The problem attributed to Alhazen (the Latinized name of Ibn al-Haytham (965-1045)) is to find a point of reflection on the surface of a spherical mirror in relation to two points, the eye and the visible object.
The diagram and text are printed using a method that Huygens claimed he had invented, making the acid bite all the way through the plate and inking over it, as with a stencil.
Christopher Wren had come up with a similar copying method earlier in 1662.
                            
                            
                        
                            
                            
                            The diagram and text are printed using a method that Huygens claimed he had invented, making the acid bite all the way through the plate and inking over it, as with a stencil.
Christopher Wren had come up with a similar copying method earlier in 1662.
                                Object history
                            
                            
                                C. Huygens and R. F. Slusius, 'Some letters exchanged between Monsieur Slusius and Monsier Hugenius, about a considerable optic problem (the point of reflection in a concave and convex mirror) of Alhazen', Phil. Trans., vol. 8, no. 97 (October 1673), pp. 6119-26, tab. 2, fig. 1.
The covering letter dated 26 June 1669, ElL/H1/64, is transcribed and translated in The Correspondence of Henry Oldenburg, ed. by A. Rupert Hall and Marie Boas Hall, 13 vols (Madison: University of Wisconsin Press; London: Taylor and Francis, 1965-86), vol. 6, 42-46 (no. 1213). The editors note that the enclosure regarding the solution to Alhazen's problem, with figures printed using a 'new' method devised by Huygens himself, is no longer found in the Royal Society's archives. However, this is the enclosure that accompanied the original letter.
                            
                        
                            
                            
                            The covering letter dated 26 June 1669, ElL/H1/64, is transcribed and translated in The Correspondence of Henry Oldenburg, ed. by A. Rupert Hall and Marie Boas Hall, 13 vols (Madison: University of Wisconsin Press; London: Taylor and Francis, 1965-86), vol. 6, 42-46 (no. 1213). The editors note that the enclosure regarding the solution to Alhazen's problem, with figures printed using a 'new' method devised by Huygens himself, is no longer found in the Royal Society's archives. However, this is the enclosure that accompanied the original letter.
                                Related fellows
                            
                            
                                Christiaan Huygens (1629 - 2006, Dutch) , Natural philosopher
Henry Oldenburg (1612 - 1677, German) , Scientific correspondent
                            
                        
                            
                            
                            Henry Oldenburg (1612 - 1677, German) , Scientific correspondent
                                Associated place