The establishment of the Silurian system was followed by that of the Devonian system, an investigation in which Murchison assisted, both in the south-west of England and in the Rhineland. Soon afterwards Murchison projected an important geological campaign in Russia with the view of extending to that part of the Continent the classification he had succeeded in elaborating for the older rocks of western Europe. He was accompanied by Édouard de Verneuil (1805–1873) and Count Alexander von Keyserling (1815–1891), in conjunction with whom he produced a work on Russia and the Ural Mountains. The publication of this monograph in 1845 completes the first and most active half of Murchison's scientific career. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1840.