Definify.com

Webster 1913 Edition

Noun.

(Naut.)

An instrument formerly used at sea for taking the altitudes of heavenly bodies, now superseded by the sextant; – called also

cross-staff

Brande & C.

Noun.

An instrument used at sea, for taking the altitudes of heavenly bodies; called also cross-staff.

forestaff ‎(plural forestaffs or forestaves)

(nautical) An instrument formerly used at sea for taking the altitudes of heavenly bodies, later replaced by the sextant.
(Can we find and add a quotation of Brande & C to this entry?)