Wooden backstaff or Davis quadrant made by James Woodside, Dublin, Ireland, 1733. The navigational instrument is fitted with boxwood circular scales (30°arc 0-25, 60°arc 0-65 & 1.5’ divisions) on an ebony frame with signed central strut, a Flamsteed Lens, two signing vanes with brass retaining pressure clips and brass rivets with diamond-shaped caps.