How to Measure the Earth’s Circumference


A chapter from my second book focuses on ancient and medieval endeavors to calculate the world’s circumference. The representatives of the two scholarly trends, of the “big” and “small” earth, offer their assessments, sometimes correcting their previous estimations. In spite of a great deal of mathematical geography, the extract puts forward a new proposal concerning the comparison between various standards of measurement and makes unusual conclusions. The article is embellished by the images of Eratosthenes, Posidonius, and al-Farghani.

There will be two more publications from Unit I, titled “The Miraculous Revival or the Painful Discovery”, of my second manuscript. The common thread is the reemergence of interest to geography throughout the European Middle Ages and the reanimation of classical knowledge, often rhymed with the “ancient wisdom”. Also, the first attempts to look at the real world and the classical traditions without blurring spectacles of prejudice.



Yelu Dashi


One of the aims of my study on Prester John is to find out about numerous prototypes of this mysterious character. This week I was collecting data about one of them, Yelu Dashi, the founding father of the Kara Khitai steppe empire. Forced to flee from his Manjurian homeland, a talented military commander managed to consolidate a throng of adherents who praclaimed him the Gurkhan (the supreme ruler). Later in his reign, he interfered with the struggle between the Seljuk Sultan Sanjar and one of his vassals which led to the confrontation of the Muslim and Kara Khitai armies in the Qatwan steppe outside Samarkand. The overwhelming victory of Yelu Dashi expanded his empire which encroached into Muslim lands. His wealth came from foreign trade with China on the one hand and the Islamic states on the other.

His character became epitomised by the German chronicler Otto von Freising who tells a fascinating tale about an Oriental emperor of the Three Indies, a Christian though of the Nestorian creed, who crushed a formidable Muslim army and plans to march to Jerusalem to assist his crusading brothers to wipe off the followers of the crescent from the Holy Land.