- A rod with a sliding cursor formerly used for measuring distances and heights, especially in navigation.More example sentences
- In January 1472 he made observations of a comet, using his Jacob's staff, which were accurate enough to allow it to be identified with Halley's comet 210 years (and three returns of the 70 year period comet) later.
mid 16th century (denoting a pilgrim's staff): alluding to St. James (Jacobus in ecclesiastical Latin), whose symbols are a pilgrim's staff and a scallop shell.
More definitions of Jacob's staffDefinition of Jacob's staff in:
- The British & World English dictionary