Milescu is the author of one of the first Russian works on arithmetic, "Arithmologion", which was written in 1672, based on his own Greek original. The manuscript was preserved in the
Chudov Monastery, till it was discovered by church historian Nikolay Kedrov. In his
road journal, later published under the title
Travels through Siberia to the Chinese borders, Milescu correctly described the middle course of the
Ob,
Irtysh, and
Angara rivers. He assumed the Ob to have its source in
Lake Teletskoye in the
Altai Mountains. He was also the first person to describe
Lake Baikal and all the rivers feeding the lake, and the first to point out Baikal's unfathomable depth. His works became popular with Russian elites, being found in their collections for the next century. On his way through Siberia, Milescu used the
astrolabe to establish coordinates of some settlements. His materials were later used by the
Jesuits, who took considerable interest in China. Upon returning to Moscow, he submitted to the Foreign Ministry three volumes of notes:
Travel notes and
Description of China, alongside the
Travels. In his narratives, Milescu summed up the knowledge that Russian explorers had gathered about East Siberia. Although he believed that the Amur was the largest river in the world, he listed its main tributaries without mistake. His idea that there was a vast
mountain range stretching from the Baikal to the
Okhotsk Sea, although fundamentally wrong, was widely believed by many geographers until the mid-20th century. He also heard rumours about
Sakhalin, which he supposed to be the same island as
Hokkaido, thus considerably exaggerating its dimensions.
Bogdan Petriceicu-Hasdeu believed that Milescu was the author of the first translation of the Bible into Romanian, the
Bucharest edition (printed in 1688, during the rule of Prince
Șerban Cantacuzino). However,
Nicolae Iorga and other historians have argued that there is no actual proof of this, and have proposed
Constantin Cantacuzino as the main translator. == Legacy ==