Making the Ultimate Precision Pendulum using Harrison’s Barometric compensation.

Can a pendulum ignore changes in air pressure? In this video, we move from the theory to the lathe to build a precision pendulum based on John Harrison's theories of barometric compensation. Overview: Following up on my last video where we broke down the maths and physics behind Harrison's barometric compensation theory, it’s finally time to make some chips fly! I’ll walk you through the design and the machining process. At the end we'll do some testing to see if we have a hope of achieving extreme accuracy. 00:00 Intro 00:40 Pendulum design 03:28 Maths & spreadsheet 04:44 Workshop – machining the pendulum 04:45 Making the bob 08:24 Pendulum anti-rotation block 10:46 Suspension spring clamp 15:44 Invar pendulum rod 19:08 Suspension spring & jig 20:39 Compensation tube & rating nut 21:15 Testing the pendulum 21:39 ‘Hill test’ (free pendulum run down)