Source: wikibot/jacob-s-staff
= Jacob's staff
{wiki=Jacob's_staff}
Jacob's staff, also known as a Jacob's ladder, is a type of measuring instrument used in navigation and surveying. Historically, it consists of a long vertical rod with a movable arm or crosspiece that can be adjusted to obtain angles or measurements. The staff is often equipped with sighting devices, such as telescopes or arm sights, to help in aligning it with distant objects.