1874 Transit of Venus Expedition to Hawaii

The purpose of the expedition was to obtain an accurate estimate of the astronomical unit (AU), the distance from the Earth to the Sun, by measuring solar parallax.

[2] The Sandwich Islands team was composed of seven observers - Professor George Forbes, Henry Glanville Barnacle, John Walter Nichol, Lieutenant Francis Edward Ramsden, Lieutenant E. J. W. Noble, Captain George Lyon Tupman, and Richard Johnson - plus three Sappers of the Royal Engineers.

The primary observing station was established by George Lyon Tupman on the island of Oahu in the Apua district of Honolulu.

This information was fed into the Trigonometrical Survey of the Kingdom of Hawaii, then in progress and led by Professor William DeWitt Alexander.

George Biddell Airy published an Account of Observations of the Transit of Venus in Hawaii in 1881, with more than 200 pages about the expedition.