If P is in the circumference of bbb, that path becomes an epic ycloid.
The line T on the surface bbb has also for the instant no velocity in the plane AB; for it has just ceased to move towards the fixed surface aaa, and is just about to begin to move away from that surface.
The line of contact T, therefore, on the surface of the cylinder bbb, is for the instant at rest, and is the instantaneous axis FIG.
Sorry BBB I disagree with your " proven formula to ignore scare mongers " .
The whole of the foregoing reasonings are applicable, not merely when acm and bbb are actual cylinders, but also when they are the osculating cylinders of a pair of cylindroidal surfaces of varying curvature, A and B being the axes of curvature of the parts of those surfaces which are in contact for the instant under consideration.