1882 (Oct 5) Cover bearing G.B 6d grey plate 18 tied by Wimbledon 801 duplex, addressed to "L. Darwin, Royal Engineers, Transit of Venus Expedition, Brisbane, Australia", redirected to Jimbowo, backstamped at Brisbane (Nov 23), Macalister and with a T.P.O c.d.s. Expeditions were sent to observe the 1874 and 1882 transits of Venus in order to determine the distance of the sun from the earth, but the 1882 expedition was unsuccessful due to optical difficulties. Very unusual. Photo on Page 144. (Image1)