EQUIPMENT

ALIDADE

It is a device which is kept on the plane table top for sighting the objects. There are two types of Alidades:-

1.  PLANE ALIDADE

It is metallic or wooden ruler consists of two vanes at each end. One of the vanes is provided with a narrow slit to see the object. The other vane carries a thin vertical wire in the middle. For accurate bisecting of an object, the narrow slit, the thin vertical wire and the object should be in the same line of sight. One of the edges of the alidade is graduated to measure the distance on the plane table, and is called fiducial edge.

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