One of the reasons that harness racing was less popular than horse racing has been the reservations in gamblers’ minds about the various means of starting trotting races, particularly when bets have been lost before contests were properly under way. Before mobile starting gates gained popularity in harness racing, a rolling start was used. The horses were driven in a number of circles, and the manoeuvre, if carried out correctly, arranged the horses in lines. The fairness of the start was judged by stewards at the starting line; if they judged that a racer was not fairly in line with the others, a false start would be called and the race would start again. This process was sometimes repeated several times before a fair start occurred. In the middle 20th Century, the mobile starting gate was developed.