The prospectus of the Dictionary he addressed to the earl of Chesterfield.
In 1747 Johnson sent Chesterfield, who was then secretary of state, a prospectus of his Dictionary, which was acknowledged by a subscription of X10.
Shortly afterwards (1860) he sent out the prospectus of a systematic exposition of his Synthetic Philosophy, of which the first volume, First Principles, appeared in 1862.
The prospectus promised to give an account of the chief books published throughout Europe, obituary notices, a review of the progress of science, besides legal and ecclesiastical information and other matters of interest to cultivated persons.
Johnson had, in his prospectus, told the world that he was peculiarly fitted for the task which he had undertaken, because he had, as a lexicographer, been under the necessity of taking a wider view of the English language than any of his predecessors.