Engineering:Bematist

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Short description: Ancient Greek surveyors

Bematists or bematistae (Ancient Greek βηματισταί (bēmatistaí, 'step measurer'), from βῆμα (bema, 'pace')), were specialists in Ancient Greece and ancient Egypt who measured distances by pacing.[1]

Measurements of Alexander's bematists

Bematists accompanied Alexander the Great on his campaign in Asia. Their measurements of the distances traveled by Alexander's army show a high degree of accuracy to the point that it had been suggested that they must have used an odometer, although there is no direct mentioning of such a device:

The overall accuracy of the bematists' measurements should be apparent. The minor discrepancies of distance can be adequately explained by slight changes in the tracks of roads during the last 2,300 years. The accuracy of the measurements implies that the bematists used a sophisticated mechanical device for measuring distances, undoubtedly an odometer such as described by Heron of Alexandria.[2]

The table below lists distances of the routes as measured by two of Alexander's bematists, Diognetus and Baeton. They were recorded in Pliny's Naturalis Historia (NH 6.61–62). Another similar set of measurements is given by Strabo (11.8.9) following Eratosthenes. Eratosthenes calculated the circumference of the Earth based on work of Egyptian bematists.[3][4]

Pliny 6.61–62 Strabo 11.8.9 Actual distance
Route Milia passuum 1) English miles Kilometers Deviation Stadia 2) English miles Kilometers Deviation English miles Kilometers Route
Northern Caspian Gates – Hecatompylos 1960 225 362 0.8% 227 365 main road
Southern Caspian Gates – Hecatompylos 133 122 196 2.4% 125 201 main road
Hecatompylos – Alexandria Areion 575 529 851 0.4% 4530 521 838 1.9% 531 855 Silk Route
Alexandria Areion – Prophtasia 199 183 295 3.2% 1600 184 296 2.6% 189 304 Herat-Juwain
Prophtasia – Arachoti Polis 565 520 840 1% 4120 474 763 9.7% 525 845 Juwain – Kelat-i-Ghilzai
Arachoti Polis – Hortospana 250 230 370 0.4% 2000 230 370 0.4% 231 372 main road Kelat-i-Ghilzai – Kabul
Hortospana – Alexandria ad Caucasum 50 46 74 2.1% 47 76 Kabul – Begram
Alexandria ad Caucasum – Peucolatis 237 218 351 3.2% 211 340 Begram – Charsada
Peucolatis – Taxila 60 55 89 20% 69 111 Charsada – Taxila
Taxila – Hydaspes (Jhelum) 120 110 180 4.8% 105 169 Aurel Stein’s route
Alexandria Areion – Bactra – Zariaspa3) 3870 445 716 1.6% 438 705 via Kala Nau, Bala Murghab, Maimana and Andkhui
Average 4.2% 2.8%
Median 2.8% 1.9%

Notes:
1) 1 mille passus = 1,480 meters (1,620 yd)
2) 1 Attic stadion = 606 feet 10 inches (184.96 m)
3) The route is not recorded to have been followed by Alexander himself.

List of bematists

  • Amyntas[5]
  • Baeton
  • Diognetus
  • Philonides of Chersonissos[6][7]

See also

References

  1. Tzifopoulos, Yannis (2013). "Encyclopedia of Ancient History". Encyclopedia of Ancient History. doi:10.1002/9781444338386.wbeah09247. 
  2. Engels 1978, p. 158
  3. Russo, Lucio (2004). The Forgotten Revolution. Berlin: Springer. pp. 273–277. 
  4. All data from: Engels 1978, p. 157
  5. Heckel, Waldemar: Who's Who in the Age of Alexander the Great: Prosopography of Alexander's Empire, Blackwell, 2006, ISBN:978-1-4051-1210-9, p. 26
  6. Heckel, Waldemar: Who's Who in the Age of Alexander the Great: Prosopography of Alexander's Empire, Blackwell, 2006, ISBN:978-1-4051-1210-9, p. 216
  7. Epigraphical Database: Elis — Olympia — 336–323 BCE

Bibliography

  • 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