Clocktime: Tompion & Banger Sidereal Regulator 1708, 03 Telling the Time

Thomas Tompion & Edward Banger - Sidereal Tompion Regulator No. 483 fixed sidereal hour ring, rotating GMT ring from extended hour hand.
Join Dr John C Taylor OBE from the Clocktime digital museum as he discusses telling the time of the Tompion & Banger Sidereal Regulator, circa 1708.
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So, it looks very complicated with the two chapter rings and the three hands and I think that the third hand, this brass hand, has been a later edition. So, that leaves us with Greenwich Mean Time and sidereal time. So, it's 56 and a half minutes past three sidereal time. That will enable you to set a telescope to find any star because you just have to allow you're so far round the Earth one way or the other. And the end of the hour hand is extended out to the outer dial and the outer dial will then allow you to read the time and Greenwich Mean Time to within a minute because the dial is engraved with each minute in between the main hours. You can see the end of the minute hand here pointing onto the outer dial and the outer dial is going to rotate twice in a year and so you've got here as exactly 4 o'clock and these are 5, 10, 15 minutes so it's just coming up now to 19 minutes past 4 in the afternoon. So, here you have the sidereal second hand and every tick is 0.99727of a second, so it's quite a very, very small amount quicker than a normal 1 one-second pendulum swinging. It's quite complicated, in fact it's the most complicated geared clock that Tompion made.