At intervals from 1793 to 1801 Lang was closely connected with the Prussian statesman Hardenberg, who employed him as his private secretary and archivist, and in 1 797 he was present with Hardenberg at the congress of Rastadt as secretary to the legation.
He was also archivist and then librarian of the city of Frankfort.
On the 14th of August 1789 the Constituent Assembly made Camus its archivist, and in that capacity he organized the national archives, classified the papers of the different assemblies of the Revolution and drew up analytical tables of the procesverbaux.
Motley acknowledges his indebtedness to Groen's Archives in the preface to his Rise of the Dutch Republic, at a time when the American historian had not yet made the acquaintance of King William's archivist, and also bore emphatic testimony to Groen's worth as a writer of history in the correspondence published after his death.
In 1855 he was appointed archivist at Breslau; in 1862 he became professor of history at Heidelberg, and ten years later professor at Berlin, where he was a member of the directing body of the Monumenta and a member of the Academy.
At the Restoration he was deprived of the post of archivist of the empire, which he had held from 1807, but from 1819 to 1830 (when he again became archivist of the kingdom) he held the chair of history and ethics at the College de France, and his courses were among the most famous of that age of public lectures.
After serving his native city as secretary and archivist, he became archivist to the national archives in Paris in 1866, and later librarian to the faculty of law.
When in 1805 the principalities became part of Bavaria, Lang entered the Bavarian service (1806), was ennobled in 1808 and from 1810 to 1817 held the office of archivist in Munich.
He studied at Prague and at Olmiitz, and, after travelling extensively in search of historical material, became professor of history at the university of Prague and archivist for Bohemia in 1862.
Lastly, statistical research has shown that the children of the married British clergy have been distinguished far beyond their mere numerical proportion.8/n==Authorities== - Henry Charles Lea, History of Sacerdotal Celibacy (3rd ed., 1907, 2 vols), is by far the fullest and best work on this subject, though a good deal of important matter omitted by Dr Lea may be found in Die Einfiihrung der erzwungenen Ehelosigkeit by the brothers Johann Anton and Augustin Theiner, which was put on the Roman Index, though Augustin afterwards became archivist at the Vatican (Altenburg, 1828, 2 vols.).
His indefatigable work as archivist in the time when Napoleon was transferring so many treasures to Paris is not his least claim to the gratitude of scholars.
In 1806 he was appointed secretary and archivist to the cabinet particulier of the emperor, whom he attended on his campaigns and journeys.