Patent ID: 7797845

Claim:
A hand-held, mobile, levelling apparatus comprising: an outer casing; a laser contained within the outer casing; a window in the casing for allowing laser light generated by the laser to pass through; a locator arranged to locate the apparatus on a surface such that it is placed into a generally vertical operating position; and a suspension device arranged to ensure that the laser light is automatically emitted in a horizontal plane when the apparatus is held in the generally vertical operating position, wherein: the apparatus is arranged such that the laser light is projected from the apparatus in a direction which is away from the surface on which the apparatus is located; the locator is arranged such that the apparatus is freely moveable along the surface in a vertical direction, whilst always remaining in contact with the surface, such that it can be located into a position at which the laser light is the same height as the height of a remote, visible, datum point or main datum point; and the apparatus is further arranged such that the height of the datum point or main datum point to be transferred to the surface on which the apparatus is located.