Detail from Louis-Léopold Boilly, 'A Girl at a Window', 1799 (?).
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Telescope

The first telescope was made in the Netherlands in 1608. It was made of two lenses in a tube, one convex and the other concave, and had a magnification of about three or four. News of the new invention spread rapidly through Europe, but it was the Italian astronomer Galileo who really made the instrument famous. By October or November 1609 he had made a telescope with a magnification of twenty and used it to look at the heavens. He observed the moon and the stars and discovered four satellites of Jupiter. The type of telescope shown in this painting is probably a 'Galilean telescope'.

In 1611 Johannes Kepler invented the 'astronomical telescope', which had a much larger field of view than the Galilean telescope and a much brighter, although inverted, image.

Sir Isaac Newton developed the first 'reflecting telescope' in the 1670s. It was given this name because of its use of ground, curved, mirrors. However, due to early difficulties with grinding and repolishing the mirrors, it only became widely used in the 18th century.

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