On this day in history, August 25, 1609, Italian astronomer Galileo Galilei demonstrated his first telescope to the Senate in Venice. Impressed with Galileo’s invention, the senators doubled the astronomer’s salary and made his university appointment a lifelong one. Although others had already tried to patent the telescope, Galileo brought the device to the mainstream, publishing landmark observations in 1610.
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While employed as a professor of mathematics at the University of Padua, in the Venetian Republic, Galileo set to work on his invention in the spring of 1609. He soon developed a spyglass with a magnification of three, which various inventors had already done. He then realized that the magnification was proportional to the ratio of the power of the concave (eyepiece) lens to the convex (more distant) lens.
At the time, opticians only made glasses in a narrow range of strengths, and 3 was about the best magnification available. Therefore, Galileo taught himself how to grind his own lenses. By August 1609, he had created about ninefold linear magnification.
Filed Under: Rapid prototyping
