Sailors, Scientists, Spies describes the lives of two eighteenth century Spanish naval officers. These young men, Jorge Juan and Antonio de Ulloa, first met in 1735 when they were chosen by King Philip V to represent Spanish interests on a French scientific expedition to South America.

At that time, navigation at sea could best be described as an inaccurate science, largely because of the prevailing uncertainties as to the precise shape and size of the earth. The aim of the French project was to provide answers for these age-old questions by measuring three degrees of latitude on the ground at the equator.

The experiences of Juan and Ulloa during this nine-year expedition and the subsequent scientific contributions they made to the history of eighteenth-century Spain were remarkable. they form the basis for this intriguing story which begins with their transition, as members of the expedition, from Naval midshipmen to enlightenment scientists.

After returning from South America they were sent by Spain to carry out daring spy missions in Britain, France and other European countries, to gather for Spain many of the naval and industrial secrets of the nation's old enemies. Both men later went on to have distinguished and sometimes controversial naval careers, but these were eclipsed by their engineering and scientific contributions to the industries of their country and to its Navy during the Enlightenment period.

Sailors, Scientists, Spies provides a pacy account of the fortunes of two fascinating but little-known Spanish heroes.