A Hamilton with an Illinois serial number

Jerry Treiman

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Aug 25, 2000
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Most American watches have their serial number prominently shown on the top plates and then the whole or partial number on other plates and bridges. However, some of the watches that I have focused on are not quite this way. For example, the movements that Waltham made for Howard have a Howard serial number on top but their Waltham serial number on the pillar plate (sharing the last 5 digits). Hamilton’s 12-size grade 400 (movement inherited in their Illinois Watch Co. acquisition) also have some serial number anomalies. On the barrel bridge they have the Hamilton serial number (Hxxxx) but on the pillar plate they retain their original 7-digit Illinois serial number. In the first eight-hundred grade 400 movements, randomly rebuilt from remaining gr.528 movements from both known serial number blocks (3,869,xxx and 4,018,xxx) there is no correlation between the Illinois and Hamilton numbers on the same watch. Hamilton numbered these H1001 to H1800. The next 1500 movements H2001 to H3500) were purpose-built and the Hamilton serial number is the same as the final four digits of the 7-digit serial number under the dial, as in this example --
H2183m.jpg 2183ud.jpg

The Hamilton number is H2183 and the number under the dial is 5402183. However, there are some odd things going on here. Here is a close-up of the serial number on the pillar plate.
H2183_uddt.jpg

First, what is with the “D MOD.” above the serial number? If you look carefully there appears to even be a small plug in front of the first D. I think this originally indicated the Illinois 12-size extra-thin 3rd Model from which this plate is derived, but with the "3" removed. [The “D MOD.” does not appear on all examples]. Here is a comparison of the two --
400-525.jpg

Another conundrum is the 7-digit serial number on the pillar plate. Is this an Illinois serial number or a Hamilton serial number? If it is an Illinois number it is within a block of 4,000 numbers assigned to a 12/0 grade 207 movement. Furthermore, I have recorded at least one example of a grade 207 Illinois and grade 400 Hamilton with the same serial number (5,402,392 or H2392) and several other 207s within the conflicting serial number range. Alternatively, could it be a Hamilton serial number reserved well above the known range of Hamilton numbers? I suggest that it is an Illinois number that Hamilton carelessly duplicated. The gr.400 is also known for duplicating H-serial numbers that were also used for their 12-size grade 921, so their inattention to these details is perhaps not surprising.
 

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