Dating bardou telescopes


06-Apr-2017 18:14

(Gloria Clifton, “British Scientific Instrument makers 1550-1851, 1995, Zwemmer Publishers & The National Maritime Museum, London).21.15 IMPORTANT AMERICAN KALEIDOSCOPE. Quite unexpectedly, his ongoing examination of rope fibers under a microscope ultimately lead to an interest in kaleidoscopes.

Precise focusing is accomplished by turning the large knurled focusing knob on the observer’s right, which operates with a smooth, tight action.It has a “5” element erecting system instead of the typical 4 found in telescopes from the 1750 onward.In addition, the lenses are simply loose and screwed into their retainers with a threaded ring.It seems hard to believe that instrument has survived in such pristine condition for over 220 years!