Small Gregorian Telescope, Mid-18th Century

Good model of a small reflecting telescope called Gregorian, after its English inventor James Gregory. The instrument is not signed but French, dating around 1750-1770. The optical tube measures 31 cm in length with its eyepiece. It is mounted on a ball joint that screws into a folding tripod stand. The large screw of the ball joint can be removed and screwed into a wooden support for outdoor use during travel or movement. The focal length of the smaller mirror is adjusted by the play of a worm screw attached to the optical tube. The two mirrors are original and the instrument gives a clear and frank image. Note a few defects: the external part of the eyepiece is damaged but this does not hinder the use of the instrument in any way, the period elements wedging the large primary mirror have been replaced by modern cardboards and the main tube should, perhaps, have been covered with decorative leather. However, good used condition for this travel reflecting telescope dating from the middle or, at the latest, the third third of the 18th century. Approximate height: 22cm.