Telescope by Pietro Patroni, Milan, with non-achromatic objective lens and 5-draw tube.

Dated to the first quarter of the eighteenth century, this refracting telescope was made by Pietro Patroni in Milan, Italy. The telescope has simple objective and eyepiece lenses mounted in ivory. When fully extended the five drawtubes of the instrument measure over three feet, but only eleven inches when closed. The tube of the telescope is made of card and leather, while the drawtubes are green vellum with gold decorative tooling. Unlike Galileo's telescopes this one is fitted with convex eyepiece lenses as first suggested by the astronomer Johannes Kepler in 1611. This gives a much wider field of view than in Galileo's telescopes while the inverted image can be made upright by adding an extra convex lens.