ratified in 1910, is for an "Improved mechanical motion device" that converted rotary motion which "is applied, as for instance by an Eccentric", into tangential reciprocating movement, an example application given being sheep shears. The invention, the basis of modern mechanical sheep shears, was introduced without Unaipon receiving any financial return and, apart from a 1910 newspaper report acknowledging him as the inventor, he received no contemporary credit. Other inventions included a centrifugal motor and a mechanical propulsion device. He was also known as the Australian Leonardo da Vinci for his mechanical ideas, which included pre World War I drawings for a helicopter design based on the principle of the boomerang and his research into the polarisation of light; he also spent much of his life attempting to achieve perpetual motion. Writer and lecturer Unaipon was obsessed with correct English and in speaking tended to use classical English rather than that in common usage. His written language followed the style of John Milton and John Bunyan. Unaipon was the first Aboriginal author to be published after he was commissioned in the early 1920s by the University of Adelaide to assemble a book on Aboriginal legends. From 1924 onwards he also wrote numerous articles for the Sydney Daily Telegraph. He published three short booklets of Aboriginal stories in 1927, 1928 and 1929. In this time he wrote on topics covering everything from perpetual motion and helicopter flight to Aboriginal legends and campaigns for Aboriginal rights. Unaipon was inquisitively religious, believing in an equivalence of traditional Aboriginal and Christian spirituality. His employment with the Aborigines' Friends' Association collecting subscription money allowed him to travel widely. The travel brought him into contact with many intelligent people sympathetic with the cause of Aboriginal rights, and gave him the opportunity to lecture on Aboriginal culture and rights. He was much in demand as a public speaker. Many times he was refused accommodation due to his race. He said "...in Christ Jesus colour and racial distinctions disappear..." and that this thought helped him at such times. Unaipon was the first Aboriginal writer to publish in English, the author of numerous articles in newspapers and magazines, including the Sydney Daily Telegraph, retelling traditional stories and arguing for the rights of Aboriginal people. Five of Unaipon's traditional stories were published in 1929 as Native Legends, under his own name and with his picture on the cover. Some of