Hamilton Watch Co., Columbia, PA, USA, c.1950 No.4E019
Two-day, Model 221, 4 Orbit marine chronometer ZBA4526

Box/Mounting The chronometer is housed in a plain mahogany guard box of rebated housing construction, measuring 237mm high, 323mm wide and 263mm deep. The front of the upper half has the typical semi-circular downward projection, mating with a hollow in the front of the lower half, and originally having a typical, brass hook, securing the box closed over a screw head (hook and screw both now missing). The base of the lower half of the box projects on either side, forming ‘tabs’ with curved ends by which the box may be screwed down to the deck through a hole drilled in each of them. On the front of the upper half of the box is a white plastic label engraved: HAMILTON WATCH CO. / LANCASTER. PA. U.S.A. The back of the box is marked in black crayon: Sierra. The two-part, 25mm wide leather carrying strap is now broken and almost completely missing, the remains of each part fixed to the sides of the lower section by three brass screws and washers. The inside of the box is fitted out with green felt covered padding, into which the chronometer fits snugly.

The three tier, brass-bound, mahogany chronometer box, of rebated-housing construction, measures 194mm high, 215mm wide and 199mm deep. There are pressed brass sliding catches on the front for the box and lid. The lid of the box has a strut on the left hand side allowing it to open to just over 90 only, and the brass full-width hinge has a removable pin allowing the lid to be removed altogether. On the front of the upper section were two labels, probably of the usual Model 21-type, but both now missing, only the screw holes being present. The box has a brass bead running along the centre of the junction on the lower section, mating with a groove in the junction of the upper section and forming a dust seal when closed. Fixed inside the back of the upper half is a semi-circular white plastic label, printed in black: CORK AS SHOWN BEFORE SHIPPING, CORK, ACTUAL SIZE and: SEE SHIP’S / CHRONOMETER / RECORD BOOK / (FORM N.B.S. 702) / “TRANSPORTATION” / PARAGRAPH 2 (A). The underside of the box has a green baize covering.

The box furniture is standard, with brass drop handles on the sides and lacquered brass gimbals. The upper section is on a brass full-width hinge with a strut on the left hand side allowing it to open to just over 90 only, but the strut has an opening in the slot to allow it to be disengaged so the upper half can be opened right over. This hinge also has a removable pin allowing the upper section to be removed altogether. The screw-down bezel (2 ½ turns) has a silvered sight ring, a coarse knurled edge and a flat glass over the dial. Under the bezel, scratched on the upper edge of the bowl at the 45 minute (‘IX o’clock’) position is: IX marked twice. The standard type brass bowl has a concave moulding under the bezel thread, a straight side and straight angled base with a large sink turned on the underside with a full-diameter spring-loaded dust shutter. Fixed inside the bottom of the box is a rectangular white-faced plastic plaque with rounded ends, printed in black: HAMILTON WATCH CO. / LANCASTER. PA., U.S.A. Standard later-type Hamilton-pattern rising ratchet winding key.

Dial & Hands The fine, vertical grained, silvered finish dial is 104.3mm, with Hamilton’s special ‘4 orbit’ layout, all markings machine-engraved. The dial plate is located in a recess in the brass edge with a notch fitting a pin in the brass edge at the 15 minute position, and attached from inside with 4 screws. The main minutes dial has vertical arabic five-minute numerals [00 at the top] with a seconds indication on the right, having arabic ten-second figures with straight batons at alternate five second intervals [00 at the top], and a 24 hour dial on the left, with arabic two-hour numerals and 00 at the top. The upper part of the main dial has an up-and-down indication in it, which is marked in arabic in 8 hour intervals, from 8 to 48, and is marked UP before 8 and DOWN after 48. In the lower part of the main dial is a days of the week indication [abbreviated SUN, MON, etc]. The dial is signed at the very top: HAMILTON, and at the very bottom: LANCASTER, PA., U.S.A. , and is numbered 4E019 within the hour dial, and 1947 within the seconds dial. Black patinated steel spade and poker hands with a fine, black-patinated steel, pointer seconds hand with a counter poised tail and a black-patinated steel up-and-down and day of week pointers.

Movement The movement is attached to the brass edge with three nickel-plated screws. Hamilton’s version of Nardin’s standard M.G.F. type, two-day, solid nickel alloy (employing some copper and zinc), full plate fusee movement with four pillars, all fixed with polished nickel plated screws. The general level of finish of the movement is good, with the upper surface of frame parts damascened. The pillar plate is engraved 4E019 and the upper fusee/barrel plate is engraved: MODEL 21, 14 JEWELS / HAMILTON WATCH CO. / LANCASTER, PENNA. / MADE IN U.S.A. / 4E019 . The lower balance bridge has in it a train-blocking screw actuated from the potence plate above, a peg on the end of the screw entering the crossings of the fourth wheel when employed. There is also a large hole in the pillar plate for access to one of the lower balance bridge screws to enable removal of the bridge without dismantling the sub-frame. Where pivots are not run in jewel holes they have gilt-brass bushes in the nickel alloy frame. The motion work under the dial is based on the Model 21, with the same up-and-down work and cannon pinion. The cannon pinion has a black plastic pipe over it to control the height of the central minute hand, and the off-set hour wheel runs into the minute pinion from a separate stud. A second ‘minute wheel’, on a separate stud and identical to the minute wheel and pinion, runs into it 1:1, and the secondary minute wheel’s pinion drives another wheel on a separate stud. A small pinion on this wheel drives the day of the week wheel which itself is run on another stud.

The inverted barrel and cap, which is secured with 5 screws into the edge of the barrel wall, are both in brass, the barrel having a raised lower edge to prevent the chain from sliding off during assembly/dismantling. The set-up ratchet and click, mounted under a bridge on the upper plate, are in steel. The barrel has a fixed steel hook and an additional steel hooking piece in the barrel at the outer terminal of the mainspring, for protection of the hooking. This piece runs just under three quarters of the way round the inside of the barrel, a fixed hook in the mainspring proper locating on the edge of the piece. The fusee, which has a brass cap, continental stop-work and Harrison’s maintaining power with a brass ratchet, has a pipe round the winding square with a captive, spring-loaded dust trap within and a plastic seal above.

Four-wheel train plus great wheel, the wheels in gilt brass, the third wheel run within an opening in the pillar plate, on a third/fourth wheel bar.

Escapement, Balance & Spring and Jewelling The Earnshaw-type spring detent escapement has a Beryllium-Copper detent mounted on a nickel block on the potence plate. The detent has a bifurcated spring and a screwed on, Elinvar passing spring cranked out to run parallel to the detent blade, and with a red V-section jewelled locking stone. The impulse roller, which is separate from the discharge roller, has a radially set, red impulse jewel and the discharge roller has a similar stone inset.

The two-arm Hamilton ‘ovalising’ balance, which is scratched under the arms: 019, has straight, narrow arms (invar) and the rim (stainless steel) has four, brass compensation screws on each side and nickel-plated steel, mean-time nuts are mounted on fixed threads at the end of the arms. Small, nickel-plated steel ‘vernier’ mean-time nuts are mounted on the rims just to one side of the balance arms. The balance is secured to the staff with the improved collet and the separate impulse roller is part No.42264 [scratch-marked as 4] and of 0.250”dia.

The ‘Elinvar Extra’ helical balance spring, which has a brown colouration, has terminals on both ends, the upper terminal with a stud (scratched on its upper surface: 4E019) fixed under the balance cock. The jewelling, which is mounted in brass or nickel settings, extends to the balance and escape wheel pivots with endstones, the holes on both the fourth wheel pivots and on the lower third wheel pivot, and the escapement parts as mentioned.

History Work at the factory began in early February 1948 and the chronometer was adjusted for isochronism (one of the last jobs to be undertaken) on 26 February. However, it is unclear when the chronometer was sold as there is no entry after 4E0016 in the ‘date finished’ page for the 4E chronometers. There may have been some delay in sale, as 4E0016 was only recorded as finished in May 1951. The Hamilton records do however have additional cards for this instrument, showing that it was ‘reconditioned’ in 1953 and, on a ‘duplicate card’ that it was cleaned and oiled in March 1969. In July that year, it was apparently in the ownership of the well-known U.S. watch collector Arnold F.T. Kotis of New York. The chronometer was purchased by the RMG at Christies London on 4 July 2007 for £8,400 incl.