A method of dispensing bolts includes a step of forming a column of bolts on top of one another. The device for measuring the direct component of alternating current comprises a current-carrying wire around which there is located a magnetic core provided with a gap in which a magnetic field sensor with insulated terminals is located and it comprises a shorted compensating winding or which is made in the form of a single turn coil placed on the core. A second mechanism is provided for moving the imaging device in association with the condensing device, while maintaining thereon the image of the radiant area.