Leaderboard

I don't know what the correct value is, but you never re-time a mov.t based on the lift angle, which has no influence whatsoever on rate and beat error. Only amplitude is influenced, by about 1.5 deg of instrument reading for each one of lift angle, but since amplitude can vary easily by 5 - 10 deg depending on power charge and position, that is also negligible. Now, this discussion has been had already, complete with formulas and experimental confirmation, as soon I can find the original thread I'll merge this one into it.

I forgot a picture of the case

I have the DeCarle book but annoyingly can't find it, I do remember its very good and has just about every complication you would encounter including split seconds mechanisms, repeaters and calendar complications its a great book it also has an excellent section on explaining various chronograph scales and slide rules such as telemeters, tachymeter and pulsation markings and decimal markings so yes I would highly recommend it.

This is a recent acquisition all it really needed was a good cleaning and a mainspring. It is a 6size Seth Thomas made for Montgomery Wards stores. It.s in a beautiful gold box hinge case.

I've got a small monocular hand held microscope 80x mag, its a cheapie from maplins, cost a few quid and is perfect for quick inspections of jewels, hairsprings etc etc

I think you're going to find you don't have to be that exact on this. I've attached an image to explain about the poising problem. So as you can see from the Image the lower the amplitude the greater the effect of positional errors. Then as you approach 220 positional errors are no longer a problem. Then as you go over 220° positional errors are less of a problem. This is why it be nice if your watch was always running at least 220 or higher it minimizes positional errors. As far as faultfinding goes and the amplitude has to be correct I would really like to see some examples where having incorrect amplitude prevents you from doing any of these. Most users of timing machines leave them at the default 52°. Then what about the days of the paper tape machine they didn't even have the lift angle only a paper graphical display?