Galileo Galilei the use of the compasses for 120 lire. In about 1593, Galileo constructed a thermometer, using the expansion and contraction of air in a bulb to move water in an attached tube. In 1609, Galileo was, along with Englishman Thomas Harriot and others, among the first to use a refracting telescope as an instrument to observe stars, planets or moons. The name "telescope" was coined for Galileo's instrument by a Greek mathematician, Giovanni Demisiani, at a banquet held in 1611 by Prince Federico Cesi to make Galileo a member of his Accademia dei Lincei. The name was derived from the
Janssen (lunar crater) lies entirely within the outer wall, in the northeast quadrant of the floor. A number of other lesser, but still notable craters mark the crater floor. Connected to the northeast rim is Metius, and to the north is the heavily worn Brenner. Southeast of Janssen are the co-joined craters Steinheil and Watt. Astride the southwest wall is the smaller Lockyer. Further to the east, although appearing nearby due to elongation, is the huge Vallis Rheita. In the southern two-thirds of Janssen can be discerned the remains of a large, concentric crater, the wall of which is overlaid by Fabricus. The