Arc, d'

From 1998, the conversation around colorblindness in France, and the hyphenated identities of the footballers whose faces were illuminated on the Arc d’Triomphe, became a topic of national and global concern.

The compasses being set to this distance g, we may rest one compass point at c, and mark the arc f h, and the distance between arc h and arc d, measured on the line a b, is the difference between the points c, f when measured around the circle p p, and straight across, as at g.

The point a being found by trial with the compasses applied to the curve b, the circle a c may be struck, and the location for the centres from which the face arcs of each tooth must be struck will also fall on this circle, and all that is necessary is to rest one point of the compasses on the side of the tooth as, say at e, and mark on the second circle a c the point c, which is the location wherefrom to mark the face arc d.

Now suppose we employ cutting edge c as a centre and swing the cutter until its axis or centre moves along the arc d to the dot e, and it is evident that during this motion the heel of the tooth will have approached the axis of the emery wheel and that more clearance will therefore have been given to the cutting edge c.

It is essential in this case that the rollers r and r′ and the centre upon which the cam revolves shall all three be in the arc of a circle whose centre is the axis of x, as is denoted by the arc d.