In 1913, George Julius installed a building-sized, all mechanical odds-calculating computer at Auckland, NZ's Ellerslie racetrack, powered by huge iron weights that slowly pulled down bike chains over sprockets, driving the clockwork device as it "totalised" all the bets laid on horses at the track, keeping the odds in constant balance so that all the bettors were effectively betting against one another, in a system called "pari-mutuel" betting.
Pari-mutuel betting began in 1860 and spread all over the world as an efficient, financially sound and theoretically transparent way to make odds on sporting events, but it required difficult real-time calculations, and these were susceptible to manipulation by unscrupulous oddsmakers, even with the addition of primitive mechanical calculators.
Julius was a mechanical engineer with a background in railway and timber engineering, and he began to tinker with automatic mechanical calculators as election tabulators. After he was rebuffed by elections authorities in Australia, he was introduced to racetrack gambling by a friend (Julius's father was a high-ranking Anglican cleric and the family were not gamblers).
The all-mechanical calculating engine occupied the "tote house," a multi-storey building at the Ellerslie track for only five years before it was replaced with a much more efficient (but less steampunk) electromechanical calculator. That calculator was the prototype for the products eventually sold to racetracks around the world by the new Auckland Totalisators Limited company, which led the market for the next fifty years.
The betting process begins when a ticketing agent pulls a lever corresponding to the horse chosen by the bettor. This lever tugs at one of the 900 steel wires running overhead—one wire per horse, per ticket window at thirty apiece. You can just make them out in the upper right corner of this picture. Bets were taken in the smallest monetary units, and each pull of the lever incremented the bet.
In order to convert the parallel input from all the ticket windows to serial tallies for each horse, Julius invented a mechanism he called a shaft adder. The totalisator at Ellerslie racetrack had one of these mechanical differential adders for each horse. A shaft adder consisted of several sets of epicyclic gears situated along a common shaft. An escapement wheel attached to each gear set prevents it from rotating freely. The shaft adders are summed together to form the running grand total, which is displayed at the top of the tote board. A separate mechanism gave approximate odds using the horse's current bet total, the current grand total, and some trigonometry.
TOTE BOARDS: THE IMPRESSIVE ENGINEERING OF HORSE GAMBLING
(Images: Rutherford Journal)