In 1802 the board of agriculture requested him to direct his attention to agricultural subjects; and in 1803, with the acquiescence of the Royal Institution, he gave his first course of lectures on agricultural chemistry and continued them for ten successive years, ultimately publishing their substance as Elements of Agricultural Chemistry in 1813.
The first course of lectures under the benefaction was delivered in 1820.
In 1806 and 1807 he delivered a course of lectures at the Athenee on the language and literature of France from the earliest years; and in 1808 at the emperor's request, he prepared his Tableau historique de l'etat et du progres de la littrature francaise depuis 1789 jusqu'd 1808, a book containing some good criticism, though marred by the violent prejudices of its author.
His residence there from 1799 to 1806 was unbroken save for a course of lectures during the summer of 1805 at Erlangen, where he had been named professor.
In 1812 he was appointed professor of chemistry to the Apothecaries' Society, and delivered a course of lectures before the Board of Agriculture in place of Sir Humphry Davy, whom in the following year he succeeded in the chair of chemistry at the Royal Institution, London.
Sir Isaac Newton was probably the discoverer of astigmation; the position of the astigmatic image lines was determined by Thomas Young (A Course of Lectures on Natural Philosophy, 1807); and the theory has been recently developed by A.
In 1869 he gave a course of lectures at Harvard on the Positive Philosophy; next year he was history tutor; in 1871 he delivered thirty-five lectures on the Doctrine of Evolution, afterwards revised and expanded as Outlines of Cosmic Philosophy (1874); and between 1872 and 1879 he was assistant-librarian.
In 1671 scarcely less enthusiasm was roused in Montpellier; and in 1680 he opened a course of lectures at Paris, with such acceptance that hearers had to take their seats in advance.
On the death of Charles Alston in 1760, Cullen at the request of the students undertook to finish his course of lectures on materia medica; he delivered an entirely new course, which were published in an unauthorized edition in 1771, but which he re-wrote and issued as A Treatise on Materia Medica in 1789.
Three years later, being thrown upon his own resources, he began a course of lectures in his own house, and formed literary connexions with Le Courrier francais, Le Globe, L'Encyclopedie moderne, and La Revue europeenne.