Architectural drawing displaying a classical Roman stadium lap counter featuring seven large egg-shaped indicators positioned atop a columned structure 插畫檔

This nineteenth-century linear schematic depicts a specialized athletic counting device, known historically as an ovum, which consisted of seven large wooden or stone egg-shaped spheres supported by a small four-columned portico. Originally introduced during the 1st century BC in ancient Italy to assist spectators within large racing stadiums like the Circus Maximus, these sculptural indicators functioned as a visual lap counter during high-speed chariot competitions. Each time the competing teams completed one full circuit around the central dividing barrier, stadium officials would lower or remove one of the prominent egg shapes, ensuring that both the Roman audience and the competing charioteers could accurately track the remaining distance of the seven-lap race.