On his return to Utrecht he took the degree of doctor of laws (March 1688), and after travelling through Switzerland and part of Germany, settled down to the practice of law, without, however, abandoning his classical studies.
After a brilliant college career, which made him doctor of laws and a qualified barrister at nineteen, he was appointed counsel to the Breton estates and in 1775 professor of ecclesiastical law at Rennes.
While in England he resided at Corpus Christi College, Oxford, where he was made doctor of laws and lectured on philosophy.
His services to education in Scotland were now recognized by the conferment of the honorary degree of doctor of laws by the university of Edinburgh in 1871.
On his return from a journey to Dalmatia, for the purpose of selecting and fortifying the port of Trieste, he was nominated, November 1703, Savilian professor of geometry at Oxford, and received an honorary degree of doctor of laws in 1710.
He continued to study history in London, and at Berlin and Gottingen, graduating as doctor of laws at Gottingen in 1816.