A fine and large early 19th Century brass and ebony 'T'-framed octant, the cross-arm with ivory plaque signed E Dyer, ivory main scale divided to 90 degrees with incised cypher 'S.B.R.' (Spencer, Browning and Rust) brass index arm 16in (41cm) radius, three shades adjustable back side, trade label of James Bassnet, Liverpool in stepped 'A'-shaped oak carrying case