The miniature set on the cover is a view of Tivoli after one of Joseph Vernet (1714-1789) most celebrated paintings for François de Régny (1706-1779), French Consul in Genoa. This painting was later engraved by Pietro Martini (1738-1797) in the 1770s (see L. Lagrange, Joseph Vernet et la peinture au XVIIIème siècle, with the texts from the Livres de raison and some other unpublished documents, Paris 1864, p. 475) and given the imagined title: View of Spoleto.
Vernet became the reference point throughout Europe for landscape and marine paintings sought after by wealthy European collectors. This View of Tivoli was without question one of the most striking examples of his mature work and was painted when he was at the peak of his career, in 1753.
Tivoli became one of the most depicted sites favoured by 18th century painters and by visitors on the Grand Tour.

View of Spoleto, engraving after Joseph Vernet (French, Avignon 1714–1789 Paris) by Pietro Antonio Martini (Italian, Trescali 1738-1797 Parma) circa 1770 © The Metropolitan Museum, New York.