AbstractThe Zeiss subtense bar and precise traversing equipment consists basically of sets of tripods and tribrachs into the centres of which fit the Theodolite Th.3, traversing targets, optical plummet and the subtense bar, all fitted with identical plugs for insertion into the sockets. Thus subtense bar, traverse target and theodolite are readily interchangeable with the optical plumbing device without disturbing either the centring or the level of the tribrach.