Sphaera - Peter Dollond answers Jesse Ramsden - A review of the events of the invention of the achromatic doublet with emphasis on the roles of Hall, Bass, John Dollond and others.
galileo.rice.edu The Galileo Project > Science > The Telescope by Al Van Helden "The Hague discussed the patent applications first of Hans Lipperhey of Middelburg, and then of Jacob Metius of Alkmaar... another citizen of Middelburg, Sacharias Janssen had a telescope at about the same time but was at the Frankfurt Fair where he tried to sell it"
umich.edu
astro.lsa.umich.edu
Parabolic mirrors were used much earlier, but James Short perfected their construction. See "Reflecting Telescopes (Newtonian Type)". Astronomy Department, University of Michigan. Diarkibkan daripada yang asal pada 2009-01-31. Dicapai pada 2014-02-08.
web.archive.org
Parabolic mirrors were used much earlier, but James Short perfected their construction. See "Reflecting Telescopes (Newtonian Type)". Astronomy Department, University of Michigan. Diarkibkan daripada yang asal pada 2009-01-31. Dicapai pada 2014-02-08.
