Hour Circle The lamp near the eye-end illuminates the field or the wires at pleasure, as well as the position circle of the micrometer and the declination.

Hour Circle

The lamp near the eye-end illuminates the field or the wires at pleasure, as well as the position circle of the micrometer and the declination

An hour circle attached to E P and a declination circle attached to the box containing the mirror N, both of which can be read or set

But when much larger instruments are required the hour circle becomes inaccessible from the floor, and means have to be devised for reading both