A plummet for ascertaining verticality is described, comprising a disc-shaped body having a central aperture. The disc is suspended by means of a line in a position radially parallel to the ground or work surface. Upon lowering it to rest on the ground, marking of the point of verticality may easily be effected at the center of the aperture. The plummet may be used in combination with an accessory plummet disc of substantially the same diameter as the suspendable plummet and which serves as a target to be placed upon the floor or like surface; vertical alignment can thus be ensured when the suspendable plummet is concentric with the target plummet disc.
