The first horse racing starting barriers were simple ropes or occasionally wooden barriers behind which the horses stood. The first automated design was pioneered in Australia and was first used at an official race meeting in 1894. Alexander Gray had concluded that the flapping of a starter's flag distracted the horses. An impetus for his invention was a £5 fine received by his son, Reuben, a jockey, for allowing his mount to step over the white chalk line that marked the start. His machine was first tried out at Canterbury Park Racecourse in New South Wales in February 1894. Gray's prototype consisted of a single strand of wire at about the height of the horse's head that was attached to a spring at either end. When the device was activated the barrier sprang up and away from the horses. Gray's single-strand barrier was among those first used. Versions of barriers designed by Alexander and Reuben Gray were installed at race tracks in Australia and overseas between 1894 and about 1932. By the 1920s the single strand barrier had evolved into a spring-powered five-strand device designed by Johnstone and Gleeson, but based on Gray's prototype, that resembled a strongman's chest expander. Barriers assured fair starts to races. Fair race starts encouraged owners to enter horses in races and punters to bet, and they contributed to changing horse racing from a social sporting event into a billion dollar industry.