One step at a time

July 330 B.C. Alexander the Great makes his entrance at the front gates of Hecatompylos - the capital of the weakened Parthian Empire. He had marched, he had waged war and he had conquered… again. While his armies recuperated, his mind would already imagine his next glorious triumphs. But, his wanderings would be delayed: his new acquisitions needed order and direction. In this, one role would get special attention from the emperor, a role that we largely overlook. Before even calling his architects, his advisors or even his generals, he would call his bematists.

Bematists can be seen as ancestors to our modern surveyors - experts in measuring large distances. Learning the distance between cities is a crucial part of assessing the strategic importance of cities for warfare, trade, communication and general logistics. Besides their importance, bematists deserve our respect for their incredible skill. To understand that, you must consider HOW they measured these distances. “Bematist“ comes from the Greek word bēma which literally means “step“ or “pace“. Yes, bematists measured distances by counting the number of steps they took. The bematists used their steps as a unit of measurement, relying on their consistent and rigorous stride. The number of paces would then be multiplied by the length of a typical step to estimate the distance.

Going back to Hecatompylos, Alexander assigned two of his bematists, Diognetus and Baeton, to measure the distance between Hecatompylos and Alexandria Areion. This distance roughly corresponds to the 855 kilometres between western Khurasan in Iran and Herat, Afghanistan. Using the upper estimate for modern stride length - about 75 cm - their task would require them to count approximately 1,140,000 steps. This is what we walk in half a year.

Both bematists chose their path, prepared their supplies and went out counting.

Their accuracy is truly unbelievable.

According to records from Pliny the Elder and Strabo, they would respectively count 851 and 831 kilometres. This corresponds to a maximal error of 2%, about the same as modern instruments in various industries. Such a modest error can easily be explained by the fact that roads have considerably changed since Alexander‘s time. In truth, the measures written in those records are so accurate that many modern historians cannot believe their veracity. Some have proposed that bematists used mechanical devices for their measurements, similar to the odometer prototyped by Heron of Alexandria some centuries later.

Bematists were not limited to military affairs. In ancient Greece and Rome, bematists were predictably tasked with creating maps or conducting surveys for construction projects, military campaigns, or territorial boundaries. They would also find usage in agriculture and commerce. Turns out that measuring skills are indispensable in transactions, land ownership and determining the size of plots. The Silk Road relied heavily on them to stay connected. Eratosthenes estimated the circumference of the Earth using data gathered by bematists. His remarkable accuracy would not have been possible without the expertise of the bematists themselves. Who knows what other wonders relied on their silent dedication through the years?

Today, with the advent of precise measuring tools the profession has become nothing but obsolete, even more so with innovations like GPS. Yet, the legacy of bematists endures in activities like hiking, where pace counting is still occasionally used to measure distances. Even now, bematists stand as symbols of the will, perseverance, and ingenuity of our ancestors. While we’ve made tremendous technological advances, their stories remind us to reflect on what we often take for granted and strive to better ourselves. But, like anything else, this can only be achieved over time - one step at a time.

See you next time,

References

Tzifopoulos, Yannis (2013). "Bematists". In Bagnall, Roger S.; Brodersen, Kai; Champion, Craige B.; Erskine, Andrew; Huebner, Sabine R. (eds.). Encyclopedia of Ancient History. doi: 10.1002/9781444338386.wbeah09247
Engels, Donald W. (1978). Alexander the Great and the Logistics of the Macedonian Army. University of California Press, Los Angeles, 1978, ISBN: 0-520-04272-7
Natural History, Pliny the Elder
Russo, Lucio (2004). The Forgotten Revolution. Berlin: Springer. pp. 273–277.
Arrian, John Rooke (1813). Arrian's History of the expedition of Alexander the Great: and conquest of Persia. J. Davis. p. 256.