Encyclopædia Perthensis

[1] Morison went into partnership with Colin Mitchel and Co.[2] The Encyclopædia was issued in weekly instalments from 1796 to 1806, then republished in a 23 volume set in 1806.

The first edition had the subtitle "Universal dictionary of knowledge, collected from every source and intended to supersede the use of all other English books of reference.

The subtitle was changed to "Universal dictionary of the arts, sciences, literature, &c. intended to supersede the use of other books of reference.

The main contributor and editor was Alexander Aitchison, member of the Royal Physical Society of Edinburgh.

[5][6] The majority of the 370 plates and maps claimed by the second edition, where credited, are signed T Clerk Sculpt.