cover RATANUI: 1892 (Jan.) envelope registered to Caversham, bearing 1882-1900 1d. and 2d. vertical pair twice cancelled "Ratanui", marked "Post Office Caversham To-call" and with Caversham c.d.s. at right, Dunedin Registered oval d.s. in violet on reverse; tear at top left and flap missing though a most unusual cover