Tin-plate game. It consists of a spinner with eight unequal areas. Each area is assigned to a horse and the bigger the are allocated, the shorter the odds for that horse. Players just place their bets and spin the spinner. After the result, pay the winners and take in the losing bets. I suspect that it was assumed that you would use counters as the 'money' and the one with the most counters after an agreed number of races, wins. I can see no reason why adults might play this by using real money instead of counters.