Two Dutch friends, Constantijn Huygens (von Zuylichem), father of the more celebrated Huygens, and Hoogheland, figure amongst the correspondents, not to mention various savants, professors and churchmen (particularly Jesuits).
Ardently devoted to the service of humanity, he projected a scheme for a general concourse of all the savants in Europe, and started in London a paper, Journal du Lycee de Londres, which was to be the organ of their views.
A conference of Catholic savants, held in 1863 under the presidency of Dellinger, decided that authority must be supreme in the Church.
He corresponded with many of the European savants of his day, and contributed largely to the Ada Eruditorum of Leipzig.
His later years were saddened by circumstances connected with a romantic attachment he had formed for Mademoiselle de Lespinasse, whose acquaintance he made at the house of Madame du Deffand, a noted resort of literary men and savants.