What did David Unaipon invent?

Answer 1

Unaipon took out provisional patents for 19 inventions but was unable to afford to get any of his inventions fully patented. His most successful invention (provisional patent 15 624), a shearing machine that converted curvilineal motion into the straight line movement which is the basis of modern mechanical shears, was introduced without Unaipon receiving any financial return and, apart from a 1910 newspaper report acknowledging him as the inventor, he received no credit. Other inventions included a centrifugal motor, a multi-radial wheel and a mechanical propulsion device.