A wonderful book amounting to something akin to an early 19th-century version of the Masked Magician, in which the reality behind various tricks and illusions of the day are exposed - all taking place via the medium of a series of letters between W.F.P (the author William Frederick Pinchbeck) and a mysterious A.B., the recipient of the former's knowledge. The epistolary unveiling begins with arguably the most enigmatic of the tricks listed, that of the "Learned Pig", or as the excellent frontispiece refers to it "The Pig of Knowledge". In this trick, which took London by storm in the 1780s, a pig is taught to respond to commands in such a way that it appears to be able to answer questions through picking up cards in its mouth. Several years before the publication of his Expositor, Pinchbeck had himself toured his own "Pig of Knowledge" to all the major towns of the U.S. Union including, so he claims, once introducing the pig to President John Adams to "universal applause". In addition to the pig trick, as the brilliantly lengthy title of the book declares, other tricks unravelled by Pinchbeck in subsequent letters include "invisible lady and acoustic temple", "penetrating spy glasses" and the rather marvellous sounding "philosophical swan".