Did Newton do much with rotating rigid bodies (torque, angular momentum,
moment of inertia, etc.), or were those later developments? If later, who
were the leading lights in the explication of the mechanics of rotating
rigid bodies? The cross product hadn't been invented in Newton's day. Or
maybe torque goes back to Archimedes and his levers. One web site
(http://astron.berkeley.edu/~jrg/ay202/node63.html) attributes the
rotational version of N2 to Euler.