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    Re: Lindbergh-Weems Second-Setting Watch
    From: Ed Popko
    Date: 2018 Sep 26, 11:21 -0700

    Tony,

    You could rotate the bezzle to account for the EoT but it's just as simple to use the 'slide rule' aspect of the scales, so the conversion and it to the list of partial GHA angles. You must use the right sign correction for GMT to GAT. You can add/subtract any correction such as EoT, watch running slow or fast etc. because you have a 12hr, 60min, 60sec scales to compute what partial GHA impact that correction makes. With practice, you can get most corrections down to a few seconds of arc.

    When you say your watch is 45 seconds (time wise) late, I assume you mean that it is running slow because of some mechanical or other reason if it's quartz etc.

    OK, no problem. Use the inner-most second-setting face, ignore the second hand is and see what arc angle 45 seconds converts to? Well, eyeballing it it looks like 11'12". So just add it to the list you are summing. Keep in mind, when a watch is running slow, the real event has already passed, meaning the GHA will be larger so the sign of this correction will be positive. Watch running fast is negative because the actual event was earlier, GHA is a bit smaller.

    The whole point of the second-setting watch is to have a way of setting the watch to exact second.  You know from experience with any watch, even digital, the challenge is always in getting the seconds to be correct, they change the fastest. So they way Lindberg-Weems solved it was not to try to set the mechanical sweep hand, instead, you rotate the smalr second reading time face below it. Quite a nice innovation. So by rotating that small face instead of the sweep hand, you get the exact dial-face second-hand syncronization you want. The small face is rotated with a little small knob located under the main spring winding knob. See the attached photo. Notice the second-second dial face has been rotated counter-clock wise to get zero second on the face to align with the sweep hand at the zero-ith moment.

    Popko

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