This is an Arlington Book Co. reprint of the Navy department, Bureau of ships, Overhaul, repair & handling of U.S. Navy mechanical ship chronometer model # 21 made by Hamilton Watch company, Lancaster Penna. 1948.  It has 94 pages, illustrated. 8 5/16" x 10 13/16". Very nice condition with the exception of a 1/4" tear at the bottom of the back cover...See Pix

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