"Long Compass" Part II of III: Why it works

This video explains why the Long Compass works and how to calculate Compass Angles for arcs with a large camber.

[@jeffbourne6015]

Really informative and simply explained video outlining how to make a long compass so as to draw/construct arcs to circles having very large radii. The basic geometry and maths which underpins the construction technique (as demonstrated in Part 1 of this series of 3) and demonstrates why the method works, is clearly laid out in elementary/understandable terms and is easily followed using real specific cases. The rule of thumb (approximate) method which can be used practically is provided and compared to the exact construction details. Wonderful to see useful , practical craft and the underlying fundamental principles behind it detailed and combined in this way. Thank you so much for providing and passing on these simple key sills which, sadly, rarely can be found nowadays in books or other sources.