Spirit-level incorporating battery-powered electric lamps - comprises hollow rod contg. battery and several switches connected in parallel for one-handed operation

摘要

The two indicators showing respectively exact vertical and horizontal positioning of the rod are illuminated by lamps built into it and supplied with current from an in-built dry battery via several switches distributed along the rod and wired in parallel. The illumination may be switched-on automatically by a particular movement (e.g. setting upright) or shaking of the rod, and switched-off automatically after a selectable time lapse. The battery may be rechargeable from inbuilt solar cells. USE/ADVANTAGE - Esp. in explosive atmos.; for use by builders or carpenters . Spirit-level can be welded and lighting switches operated with same hand.