Hamilton Model 21 Marine Chronometer Clock. This is referred to as the size 85 and it was the main high precision chronometer clock on board the ships. Because of their accuracy in time keeping they also used them to determine the longitude on the seas. These chronometers have a fusee and chain with the mainspring barrel to equalize pressure to the gear train and special hairspring with balance was used. Well running movement is all original and very clean. Serial number 4817: Movement serial number is 2E4817. The clock is running well and keeps good time. The mahogany case with brass gimbals is in very good shape. Comes with original outer box, all in excellent original condition. The movement is very sharp with and is in beautiful unmodified condition. The clock has sat unused for some time but runs well. Could probably benefit from a service, but keeps excellent time as it is. The inner mahogany mounting box has a nice original patina. Outer case measures 10.5 x 13 x 9.5 inches tall. Hamilton mahogany wood chronometer boxes which are the Inner Box, and large outer “Guard Case” box. It is the first 24 hours of operation after a full winding that is synchronism (stable timekeeping rate) is achieved. After 24 hours there is typically a slight drop-off in accuracy as the mainspring winds down from 24 to 48 hours. The Up Down indicator was used as a visual verification that the watch had indeed been wound-up again for that day, and every day. If the hand passes the 24 hour mark, then it is time to wind up the watch again (even though it would continue running for an entire additional day but at a slightly reduced timekeeping accuracy). The beveled clock glass is clear and in very good condition, and has no chips on the edges. The movement is complete, looks very clean, and is running strong and continuously. The gravity-leveled suspension Gimbal Ring and screws are present, are complete, and are working properly. The Time Wizard Clock Repair & Sales. Located in Independence Oregon and online! Owned and operated by Brian and Shanen Pendleton. 40 Years Experience NAWCC Member # 43717 Since 1975. Auctiva offers Free Image Hosting and Editing. Auctiva gets you noticed! Track Page Views With. Auctiva’s FREE Counter. The item “Hamilton Model 21 Marine Chronometer Clock” is in sale since Saturday, December 15, 2018. This item is in the category “Collectibles\Clocks\Vintage (1930-69)\Other Vintage Clocks”. The seller is “the-time-wizard” and is located in Independence, Oregon. This item can be shipped worldwide.