Related Object Info
4-foot Gregorian reflecting telescope
This large brass Gregorian reflector has a 4-foot focal length and an aperture of 7 1/2 inches. The barrel is 5 feet long. A finder scope is attached. The barrel is fork-mounted in a very elegant manner, with stabilizing braces. The focusing screw is very long, extending almost the entire barrel length.
The mahogany tripod and current altazimuth mounting were provided by William and Samuel Jones in 1817. The vertical arc is divided [115°]-100°-0°-40° every 30', with a vernier reading to 1' of arc. The azimuth circle is divided 0°-360° every 1°, with a vernier reading to 3'. The azimuth circle is also marked with hours in Roman numerals I-XII twice with the vernier reading to 3 minutes. As this sort of marking is customary for right ascension, the mount may have been made from parts used by W. & S. Jones for equatorially-mounted instruments.
There is a dust cover for both the main tube and the finder scope. The tripod has a brass stretcher.