Surveyor Compass:

This instrument is more or less obsolete these days and not often used for land surveying. Its construction is somewhat same to prismatic compass except that it has plane sight vane with a narrow vertical slit in place in prism. The graduations on scale vary from 0^o to 90^o with 0^o at North and South and 90^o at East and West positions marked (Figure 4(b)). The magnetic needle is edge bar type while the circular graduated scale is fixed with the box. Therefore, here, instead of whole circle bearing, reduced bearings are recorded.