Jules Jurgensen Pivot Detent Pocket Chronometer: 

Circa 1880-84.  18K original fully-signed, very heavy hunter, with gold cuvette bearing patent date, with same SS# as the movement.  White enamel dial, with Roman numerals, sub-seconds, and typical blued steel JJ “Breguet” hands.  51mm, SW /bow-set (by shifting the bow toward the dial).  Seldom-seen fully capped pivot detent escapement with gold escape wheel, bimetallic compensation balance with gold timing screws, miniature spiral for detent, 20 jewels in gold jewel-settings, Serviced by Abell Watchmakers