Telescope earliest existing record of a telescope was a 1608 patent submitted to the government in the Netherlands by Middelburg spectacle maker Hans Lippershey for a refracting telescope. The actual inventor is unknown but word of it spread through Europe. [[Galileo Galilei|Galileo]] heard about it and, in 1609, built his own version, and made his telescopic observations of celestial objects. The idea that the [[Objective (optics)|objective]], or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope. The potential advantages of using [[parabolic reflector|parabolic mirrors]]—reduction of [[spherical aberration]] and no
Scientific Revolution in the production of iron as a raw material for the Industrial Revolution. Refracting telescopes first appeared in the Netherlands in 1608, apparently the product of spectacle makers experimenting with lenses. The inventor is unknown but Hans Lippershey applied for the first patent, followed by Jacob Metius of Alkmaar. Galileo was one of the first scientists to use this new tool for his astronomical observations in 1609. The reflecting telescope was described by James Gregory in his book "Optica Promota" (1663). He argued that a mirror shaped like the part of a conic section, would correct the spherical aberration that