Description

DIMINUTIVE EARLY CASE-MOUNTED GREGORIAN TELESCOPE, probably English, c. second quarter 18th century. The 8-5/8″ x 3-1/2″ x 2-3/4″ (22 x 9 x 7 cm) mahogany or rosewood case has oak bottom and beveled slide-off lid, plus inset brass mounting plate and beautiful brass escutcheon. The brass telescope assembly mounts to the lid, by tapered steel screw and turned brass pillar to altazimuth mount. The main tube is 7-1/4″ long and 1-5/8″ in diameter, fitted with spring-loaded speculum metal primary mirror, speculum secondary mirror on adjustable mount driven by external focusing rod, erecting eyepiece assembly with two lens elements and two apertures, screw-on red solar filter, and turned end cap. The system gives remarkably fine images, even in daylight when the Gregorian design suffers from off-axis light. Condition is fine noting some darkening to the brass, a couple of replaced mounting screws, and old repair to the lock.

Various details point to an early date — the use of oak as a secondary wood, the escutcheon form, telescope design details, the diminutive size, the case-top mounting, etc. We have seen an even smaller case-mounted Gregorian by Edward Scarlett, and note James Short’s frequent use of this design.