In Lost, the DHARMA Initiative station that studied the island’s electromagnetic properties was the Swan.
The Swan was an underground DHARMA station built to investigate a powerful electromagnetic anomaly beneath the island. After the DHARMA Initiative abandoned the facility, Desmond Hume lived there and followed instructions to enter a sequence of numbers into its computer.
The station is introduced early in season two, when Jack, Kate, and Locke discover its hatch. Its apparent purpose initially seems to be a psychological experiment, but later episodes reveal that the button helped regulate the island’s electromagnetic energy.
Viewers sometimes confuse the Swan with the Pearl, another underground station nearby. The Pearl observed other DHARMA stations, while the Swan was directly connected to the recurring numbers and the island’s electromagnetic event.