Prud'hon drawing empirical measurements

This is a drawing by the Romanticism era painter Prud'hon. It is drawn on a blueish paper with some chalk and charcoal. I believe it is a study for a future painting he was working on.

Here is the original drawing. 

And this is my study of it, including (from L to R) Key marks and measurements, a quick gesture, the original with measurements/plumb lines/ and angle dropping, and the last is a little bit longer gesture.

--conor