A Waltham, 'Lever Escapement Chronometer'. and commonly called a deck watch. This one, built in c.1915, has the rare feature of  U. S. Navy markings engraved on the brass tub containing the movement and a reminder of times past.  After the United States became involved in World War One in 1917, the US Navy was aware that it did not have sufficient nautical instruments to equip the ships it had called into wartime service and was in the process of building. They asked American yachtsmen and shipping companies for the loan of their navigation instruments. Those pieces loaned to the US Navy were engraved with Navy markings and an inventory number. Some instruments were returned to their original owners after the war, and some were retained by the navy. This Waltham bears clear and crisp US Navy marks on the brass tub containing the movement.
Deck watches were used to determine longitude at sea and for precision timing for naval action. Mainly used in ships built for coastal operations such as Motor Torpedo Boats. 
This Deck Watch is the superior model with the finest quality fifteen jewel movement adjusted to varying positions, and also has an 'up/down' indicator, a device to indicate if the piece needs winding. These instruments could not be allowed to run down at sea as accurate timing had lives depending on them functioning. The 'Waltham Lever Escapement Chronometer' was produced from 1908 until the eve of World War Two. This example was made  c.1915 and features the improved up/down indicator developed around this time.
The movement is in a gimballed mount to keep the timepiece level despite the roll and pitch of the vessel. It has the caulking lock lever which secures the movement with-in the case when being carried. The polished case is brass-mounted mahogany with an upper lid, a centre, glass fronted spray cover, and the lockable main case housing the watch and access for winding. The case has excellent color and original finish. Original key.
In excellent original condition.  The eight day top quality 15 jewel movement runs fine, the dial has its original silvering with original blued steel hands. The silvered bezel retains all its original finish. The brass movement tup, gimpal ring, and the brass fittings retain their original protective laquer. The brass mounted triple tier mahogany case retains its original varnish. Original untouched condition.
Tub engraved. U S NAVY No 887.
Case Dimensions: 125 mm x125 mm x 125 mm. (5" x 5" 5").
The best and most original Waltham Deck Watch we have handled.