... for the construction of roads, railways, pipelines, tunnels and so forth• Setting-out work and control measurements onthe construction ... of sight automaticallyEasy to level upThe advantage of thisinstrument is that, as soonas the bubble is centred,the line of ... button underthe NA2 eyepiece gives thecompensator a gentle tap,so that you see the staffimage swing smoothlyaway and then float gentlyback ...