# How was curvature originally defined and calculated?

I am interested in the early history of curvature. Who defined it first and when, who came up with the name, how was it calculated before mathematicians used calculus to define $k=|α''(s)|$? Are there books or articles containing such early calculations?

• If you can form your question into something that shows research and thought then you may ask on math.stackexchange.com instead. – Ali Caglayan Oct 29 '15 at 15:18
• Previously asked at math.stackexchange.com: math.stackexchange.com/q/1502999/18398 – Joel Reyes Noche Oct 29 '15 at 15:51