How did Sir John Franklin contribute to mapping the northern Canadian coastline?

Sir John Franklin made significant contributions to mapping the northern Canadian coastline through two major overland expeditions in the 1820s, which collectively added approximately 1,200 miles (1,932 km) of new geographic knowledge to the region.1

• First Expedition (1819–1822): Franklin led a party from the western shore of Hudson Bay to the Arctic Ocean. During this journey, he surveyed a portion of the coastline east of the Coppermine River.1
• Second Expedition (1825–1827): Franklin’s team explored the North American coast westward from the mouth of the Mackenzie River to Point Beechey in present-day Alaska. Simultaneously, a second party under his command surveyed the coast eastward from the Mackenzie to the Coppermine River.1

These efforts were instrumental in charting the northwest rim of the North American continent. While Franklin’s later 1845 expedition in search of the Northwest Passage ended in tragedy, the subsequent 12-year search for his lost ships, the Erebus and the Terror, resulted in extensive additional mapping of the eastern Arctic and the Canadian Arctic Archipelago.123