Dating bardou telescopes
In addition, the lenses are simply loose and screwed into their retainers with a threaded ring.
Later telescope makers rolled their lenses into a brass seat to firmly secure them.
This impressive 19th century optical instrument is all brass, mounted atop its handsome mahogany and brass tripod.
On the top, the barrel isl labeled with the Bush trademark in gold, “C. The ocular end of the main barrel is engraved “BARDOU & SON PARIS” and is further marked with the firm’s “Trade Mark” of a “G” and “B” flanking a Caduceus -- the sign of commerce.
This is a significant observation in dating such early instruments.
Another is the draw tube wtih early form “nipple” eye piece which pulls out of the end of the main barrel with no stop – a feature added to most telescopes around 1775!
The wood shows good age free from cracks, chips or scratches.
It is 25 3/8 inches long closed and telescopes to 32 inches measured at infinity.
Overall condition is excellent, untouched, original, just like a museum would want to have it!
Also telling of its great age are two other significant features.
It has a “5” element erecting system instead of the typical 4 found in telescopes from the 1750 onward. Pre-World War II United States Navy Officer of the Deck Spyglass. The strut fits into the turned mahogany turret head.