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GALILEO GALILEI

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Galileo's telescope [1]

Inv. 2427 V.1 Galileo's telescope c.1610 [attr.] Galileo Galilei Wood, paper, copper Length 1360 mm

Description This telescope is attributed to Galileo and consists of a main tube and of two minor sections in which the objective and the eyepiece are placed. The main tube, formed by two semi-circular tubes held together by a copper thread, is covered with paper. The objective measures 51 mm in diameter, and is biconvex, but the radii of curvature of the surfaces of the two faces are not equal; the focal length is 1330 mm, the thickness at the centre 2.5 mm. The eyepiece is plano-concave and measures 26 mm in diameter; the concave side, towards the eye, has a radius of curvature of 48.5 mm; the thickness at the centre is 3.0 mm, the focal length -94 mm (the negative focal length means that the lens is diverging). This instrument can enlarge objects 14 times and has a field of view of 15'. The attribution to Galileo is due to the fact that it has elements typical of Galilean telescopes, characterised by the concave eyepiece, that the Pisan scientist made in great numbers, especially between 1610 and 1640. Prince Federico Cesi, founder of the Accademia dei Lincei, in 1611 suggested calling this instrument "telescopio"[from the Greek tele (far) and scopeo (I see)].