Inventory no. 93007 - Former Display Label
TELESCOPE EYEPIECE
c.1825
Inscribed: "The PANCRATIC Eye tube/Invented by Wm Kitchiner M.D. / Dollond London". Brass; overall length open: 14 1/8 in.; closed: 5 3/8. Three draw-tubes nest inside an outer tube that slides in a collar and flange, which screws into the end of a refracting telescope. At either end are cells each holding two lenses. The draw-tubes are marked with rings and numbers; first, from eye end, 30, 40; second tube, 50, 60, 70, 80; third tube, 90, 100, 110, 120. The rings are at intervals of 25mm., and the numbers represent magnifying powers, in this case with an achromatic objective of 24 inch focus.
This eyepiece was intended to give a wide variation in magnifying power, and to avoid the usual interchanging of eyepieces. A note on the invention of the eyepiece was read to a meeting of the Royal Society on 20 April 1820, and it was described by William Kitchiner in The Economy of the Eyes, Part II: Of Telescopes;... (London, 1825), Chapter XIII, "The Pancratic Eye-Tube, invented by William Kitchiner, M. D.". Kitchiner ends his account thus: "As I have no interest in the sale of this Eye-tube, I have considered myself at liberty to state my opinion freely upon it - it is made by Mr Dollond, and sold at £2.2s. - for £1.1s. more than the common Eye-tubes. On the old Plan, TWO Magnifying powers cost £2.2s.: with the Pancratic, you have THREE Hundred for £2.2s."
[78-16]
Presented by D. McCann, Esq.