Complex sentence: Beechey; p.59 Based on Beechey's survey, the first Admiralty chart of the island was published in 1826, and was for nearly a hundred years the only available map of the island.
Split into simpler sentences: Beechey; p.59 Based on Beechey's survey, the first Admiralty chart of the island was published in 1826. For nearly a hundred years it was the only available map of the island.