Abstract: A device for achieving visual marking of a line by a marking body is described. It relates especially to a substantially horizontal ground wire in a transfer system for high voltage electricity, at a relatively high altitude above the ground.The device comprises:a shell, especially in the form of a sphere, divided into two semispheres, carried bya fastening device, comprising clamping elements, provided to encompass the line in a first position, and to grasp the line fastening, in a second position, anda carrying device, in turn carried by a lifting device such as a helicopter or crane, which carrying means in said first position of the clamping elements carries the fastening device, and is arranged to be released, in said second position of the clamping elements, from the fastening device, so that said shell, in the form of a marking body, remains attached to said line, free from the carrying device.