Howdy,
I am editing my reply from yesterday. I misspoke and this is the correction.
Yesterday I had several long conversations going on with my brothers and both sons, about my Synchronome clock and the proposed Shortt I want to build. I then logged onto this site and in my replying to a reply, I confused myself (easily done) and misspoke.
The weight I show in the picture is the correct weight for use in a vacuum, but that weight is used for giving the impulse to the pendulum (not to time the escapement as I stated incorrectly). Late last night I realized that I misspoke, and also! that I think I know how to find the answer to my question about the size of the atmospheric weight for the Shortt.
I am now looking for the article Mr. Hope-Jones (or was it Mr Shortt?) published showing the difference of the amount of work the Shortt clock does when compared to a standard Synchronome Master clock. The article shows a bar chart and that shows the Shortt clock using 30? ergs of power (I'm easily confused again me thinks).
I think I can "back out" calculate the approximate size of the Shortt atmospheric weight from those figures, providing I can find it in the piles of paper and books I have...
The weight for running the Shortt clock in normal atmosphere is only important to someone that is setting up a Shortt clock, it saves him a lot of time, rather than closing up the clock and drawing a vacuum to adjust and test the mechanism, you insert the heavier impulse weight used in air and just run the clock in air. Of all the pictures I've seen of a Shortt, they all seem to have only the smaller weight, which makes sense, if the clock is/was running back when it was set aside/stored/dismantled, there would be no reason to install a specialty adjustment part. So finding a picture of one is I think, almost impossible.
thanks, and drive carefully.