By means of a collar round a central axis the sighting tube (now usually a telescope), together with the fixed horizon-mirror, could be moved round and clamped rigidly in any position on the scale-circle.
Ngokokujikeleza kumgca osembindini kumbhobho obonwayo(ngoku udla ngokuba yiteleskop) kunye nesipili esithe tyaba esilungisiweyo, singashukuma ngokujikeleza kwindawo kwisangqa sesikali.