[In sense 1, from St. James (Jacobus), whose symbols in religious art are a pilgrim’s staff and a scallop shell. In the other senses the name is app. more or less fanciful.]
† 1. A pilgrim’s staff. Obs.
Sometimes perhaps with a reference to Gen. xxxii. 10.
a. 1548. Hall, Chron., Hen. VIII., 10. Like two pilgrems from sainct Iames,… with palmers hattes on their helmettes, wyth long Iacobs staves in their handes.
1590. Spenser, F. Q., I. vi. 35. In his hand a Iacobs staffe, to stay His weary limbs upon.
1656. Blount, Glossogr., Jacobs Staff, a Pilgrims staff, so called from those who … go on pilgrimage to the city of St Jago, or St James Compostella in Spain.
2. a. An instrument formerly used for taking the altitude of the sun; a cross-staff. b. An instrument for measuring distances and heights, consisting of a square rod about three feet in length with a cursor which slips on the staff. c. A straight rod shod with pointed iron, and having a socket-joint at the summit for supporting a surveyor’s circumferentor instead of a tripod. (In mod. Dicts.)
1559. W. Cunningham, Cosmogr. Glasse, 106. The Astronomers staffe, also called Iacobes staffe.
1613. M. Ridley, Magn. Bodies, 105. Having a Iacobs-staffe at sea and a quadrant at land take the altitude of the Sunne.
1777. Hoole, Comenius’ Vis. World (ed. 12), 129. A Geometrician measureth the height of a Tower, or the distance of places, either with a Quadrant, or a Jacob’s-staff.
1867. Smyth, Sailor’s Word-bk., Jacob’s Staff, or Cross-staff, a mathematical instrument to take altitudes, consisting of a brass circle, divided into four equal parts by two lines cutting each other in the centre; at each extremity of either line is fixed a sight perpendicularly over the lines…. The cross is mounted on a staff or stand for use.
fig. a. 1613. Overbury, A Wife (1638), 132. He … dares beleeve nothing above primum mobile, for ’tis out of the reach of his Jacobs staffe.
a. 1734. North, Exam., I. ii. § 16. Erecting a Jacob’s Staff to take the Altitude of these wise Doings.
† 3. A staff containing a concealed sword or dagger. Obs.
1596. Thomas, Lat. Dict., Dolo, a great sparre or staffe with a small head of iron and a sword within it: a Iacobs staffe.
1606. Holland, Sueton., xiii. 159. Found there were likewise twaine … with a staffe having a blade in it [dolone] (margin Some cal this a Iacobs-staffe) and a Hunters wood-knife waiting for him.
1656. in Blount, Glossogr.
4. A plant, the Great Mullein or Aaron’s Rod.
1879. Britten & Holland, Plant-n., Jacob’s Staff, Verbascum Thapsus.
