Born and educated in England, Hargrave immigrated to Australia, where he began work in 1866 as a draftsman. He participated in expeditions to New Guinea in 1872, 1875, and 1876, and in 1878 he accepted a position as an astronomical assistant at the Sydney Observatory. Hargrave began to research the problems of flight in 1882, making careful studies of the flight of birds and insects. He constructed a number of monoplane models between 1884 and 1892, employing several methods of propulsion, including a crude compressed-air rotary engine developed in 1889. In 1893, after confirming the superior lifting qualities of cambered wings, he began experimenting with kites. Hargrave is best remembered for the introduction of the cellular kite, or box kite, as it is now known.
At Stamwell Park, New South Wales, on Nov. 12, 1894, he was lifted 4.8 metres (almost 16 feet) off the ground by four box kites of his own construction. He used models to demonstrate that a vertical tailpiece increased stability, and he built and flew a variety of models, some of which were powered by compressed air. Hargrave visited England in 1899, where he read papers describing his work and exhibited his models. The box kite, which was a significant step in the evolution of biplane aircraft structures, represents Hargrave’s most important contribution to the invention of the airplane.