Modern archaeology has led to the discovery of <answer>Han</answer> artwork portraying inventions which were otherwise absent in <answer>Han</answer> literary sources. As observed in <answer>Han</answer> miniature tomb models, but not in literary sources, the crank handle was used to operate the fans of winnowing machines that separated grain from chaff. The odometer cart, invented during <answer>Han</answer>, measured journey lengths, using mechanical figures banging drums and gongs to indicate each distance traveled. This invention is depicted in <answer>Han</answer> artwork by the 2nd century AD, yet detailed written descriptions were not offered until the 3rd century AD. Modern archaeologists have also unearthed specimens of devices used during the <answer>Han</answer> dynasty, for example a pair of sliding metal calipers used by craftsmen for making minute measurements. These calipers contain inscriptions of the exact day and year they were manufactured. These tools are not mentioned in any <answer>Han</answer> literary sources.
During which period was the odometer cart first created?
Han