Signedunsigned
FunctionSpare primary and secondary mirrors were often included with high quality reflecting telescopes in order to change the magnification of the instrument.
Historical AttributesThis spare mirror accompanied the Short telescope that was given to Harvard by Nathaniel Sparhawk, acting as guardian for his son, William Pepperrell.
Professor Winthrop used this telescope and micrometer to observe the Transit of Venus in 1769 from Cambridge.
The telescope is mentioned in several archival documents, including an inventory of 1779 that lists "A reflecting Telescope with a micrometer" and "one cannister containing one reflector for the telescope given by Sir William Pepperell."
Published ReferencesDavid P. Wheatland, The Apparatus of Science at Harvard, 1765-1800 (Cambridge: Harvard University Press, 1968), 20-21.