Refracting telescope - Dollond london - 1750-1800

Medium-sized refractor telescope. The optical tube is made of brass. The lens has a usable diameter of about 90 mm and the tube length is about 1500 mm. It is equipped with a rack-and-pinion focuser still functioning, which ends with a threading where the oculars were probably screwed in. There is a very distinctive alt-azimuth mount with micrometric movements still functioning. The mount is fitted with a metal tripod also brass. The overall weight of the telescope is considerable. To be used it needs to be placed on a stable base as the overall height of the instrument requires a riser to bring the optics to a normal and comfortable height for astronomical observation. The frontal lens shows no bubbles, streaks, spots, or mold. Type: achromatic refractor signed Dollond, whose John Dollond patent dates back to 1758. Large-scale production and marketing of these Dollond achromatic telescopes gained prominence in the following years and throughout the next century. The distinctive materials of these telescopes were the extensive use of polished brass, precision mechanical machining of gears and knobs, and the overall aesthetics typical of high-quality scientific instruments of that period. Alt-azimuth mounts with columns and fine adjustment systems like those seen in my pictures were very common in that time frame for tabletop or terrestrial/astronomical telescopes. The analyzed instrument does not show features of later telescopes, such as equatorial or motorized mounts or aluminum design, which would appear later in the 19th century. Therefore, I can safely place this type of telescope in a period between roughly 1770 and 1840. Sold together with the original mahogany box. Pickup only or shipping organized by the buyer.