Telescopic lens
Date
8 July 1672
After
Isaac Newton (1642 - 1727, British) , Natural philosopher
Object type
Archive reference number
Manuscript page number
p297
Material
Dimensions
height (Page): 312mm
width (Page): 197mm
width (Page): 197mm
Subject
Content object
Description
This diagram is part of Isaac Newton's proof that the aberration of rays from the transverse of the object-glass of his telescope would not be more than 1/50 of the glass's aperture. From Isaac Newton's letter to Henry Oldenburg dated 8 July 1672.
A copy of this diagram can be found at LBC/5/327.
A copy of this diagram can be found at LBC/5/327.
Transcription
... suppose DF be the lens; CD & EF two lines parallel to its axis, in or indefinitely neare to which all variety of difforme rays are successively incident on two opposite parts of its Perimeter. And of those rays let DH & FG bee the most refracted, & DG and FH the least refracted, interseting the former in G & H. Draw GH & produce it both ways till at m & n it occur with CD & EF also produced. Now since by my Principles the difference of refraction of the most difforme rays is about the 24th or 25th part of their whole refraction, the angle GDH will be about a 25th part of the Angle mDH and consequently the subtense GH (which is the diameter of the least space into which the refracted rays converge) will be about a 25th part of the subtense MH, & therefore about a 49th part of the whole line mn, the diameter of the lens; or, in round numbers, about a fiftieth part, as I asserted.
Transcribed by the Making Visible project
Transcribed by the Making Visible project
Related fellows
Isaac Newton (1642 - 1727, British) , Natural philosopher
Associated place