Why did Edmond Halley command the Paramore Pink in the South Atlantic?

Edmond Halley commanded the war sloop Paramore Pink between 1698 and 1700 under instructions from the Admiralty. This expedition was one of the first sea voyages undertaken for purely scientific purposes.

The primary objectives of his command were to measure the compass declination—the angle between magnetic north and true north—in the South Atlantic and to determine the accurate latitudes and longitudes of his ports of call. Halley intended to use these measurements to compile magnetic charts that would assist in navigation and potentially help solve the significant challenge of determining longitude at sea.1