Final answer:
Fifteenth century map-makers primarily studied old maps in libraries and incorporated observations from explorers and navigators rather than making calculations at sea or walking along coastlines. New navigational tools aided in the creation of maps but did not change the map-makers' primary tasks. The repair of clocks, while related to navigation, was a task for clockmakers, not cartographers.
Step-by-step explanation:
The fifteenth century map-makers spent much of their time studying old maps in libraries, collecting information about the known world through their own observations, or knowledge disseminated by others. The Ottoman admiral and cartographer Piri Reis, for instance, relied on a combination of sources, including observations made by other explorers and several Arab sources, to create his map of the known world. This approach was quite common for map-making during this period due to the difficulty of direct observation and measurements in uncharted territories.
Map-making at the time was deeply influenced by the knowledge acquired from past civilizations and contemporary explorations. Europeans, having absorbed navigational technologies such as the lateen sail, the sternpost rudder, and the astrolabe, along with the magnetic compass from non-European sources, started to venture away from coastlines into the open ocean. Such advancements helped explorers and cartographers form newer, more accurate representations of the world, even though some inaccuracies persisted due to the subjective nature of the cartography and the technological limitations of the time.
Moreover, during the Age of Exploration, it was not common for map-makers to spend time making calculations at sea or walking along coastlines due to the risks and practical challenges involved. Instead, they relied heavily on reports from explorers who did engage in direct observation. The task of repairing broken clocks, though related to the problem of determining longitude at sea, would not have been the primary occupation of map-makers, but rather skilled clockmakers like John Harrison, as highlighted in the passages.