Abstract: A precision book cutting wheel with insertable cutting bits has sockets slidingly receiving the bits and a clamping block for holding the bit in adjusted position. The sockets are inclined at an angle of 20.degree. to 40.degree. to a cutting plane normal to the axis of the wheel, and each bit has an outer cutting edge formed by a bevel parallel to and adjustable to the cutting plane.

Abstract: A circuit for switching storage capacitors in a high voltage xenon flash tube circuit includes at least one storage capacitor with parallel low and high resistance paths in series with the capacitor, switching means selecting one of the two paths and a time delay device triggering discharge of the tube at a predetermined interval, the discharge time constant of said one capacitor being a substantial portion of the triggering interval. The time delay device enables operation of the switching means a substantial time after triggering discharge.