The flora of the Hawaiian Islands has complicated relations.
The koa (Acacia koa), from the wood of which the natives used to make the bodies of their canoes, and the only tree of the islands that furnishes much valuable lumber (a hard cabinet wood marketed as " Hawaiian mahogany "), forms extensive forests on Hawaii and Maui between elevations of 2000 and 4000 ft.
In front of the city is the small harbour, well protected from all winds except those from the S.; in and after 1892 the Hawaiian government deepened its entrance from 21 ft.
The best results from extraction by diffusion have been obtained in Java, where there is an abundance of clear, good water; but in the Hawaiian Islands, and in Cuba and Demerara, diffusion has been abandoned on several well mounted estates and replaced by double and triple crushing; and it is not likely to be resorted to again, as the extra cost of working is not compensated by the slight increase of sugar produced.
While the majority of his researches bear on one or other of the subjects just mentioned, others deal with such widely different topics as the birds of Greenland, ocean temperatures, the Gulf Stream, barometric measurement of heights, arcs of meridian, glacier transport of rocks, the volcanoes of the Hawaiian Islands, and various points of meteorology.