Knowing the position of a pass or the distance between water sources could determine what an expedition was able to do. Surveying turned observations into measurements that could be compared, circulated and used by people who had never visited the ground. Maps connected fieldwork with institutions collecting geographical knowledge.
The Palestine Exploration Fund, founded in 1865, offers a particularly revealing example. Charles Wilson took part in its early work; Claude Conder and Herbert Kitchener contributed to the Survey of Western Palestine. Historical, religious and scientific enquiry drew on the skills of military surveyors. Their instruments, notebooks and collections of place names show how a published map emerged from many kinds of evidence.
Exploration should not automatically be mistaken for a secret mission. Yet geographical information could serve travel, administration and military planning alike. Following its collection and subsequent use links otherwise distant books, and opens a subject that extends well beyond any one empire or campaign.