There is a small mongraph: "The Cross Staff - Historical Development and Modern Use" Alan N Stimson and Christopher StJ H Daniel, 26pp published by Harriet Wynter Ltd 1977. It describes the Cross Staff with extracts from original English instructions for its use from 1574 and later.
This is followed by Chris Daniel's account of his use of one when he accompanied the Replica Golden Hinde which set off from Plymouth for San Fransisco in 1974 to re enact Drake's voyage. There is also a small bibliography. It is still available (I bought a copy from Rogers Turner recently). Interestingly Chris found that he could use the Cross Staff at night when use of a sextant was impossible. Peter Ransom (BSS Treasurer) uses a cross staff in teaching mathematics. I shall alert him to this thread. Patrick
