Complex sentence: He took the island as the point of junction of his double line of longitudes setting out his survey, and was given considerable assistance by the Governor of Fernando Noronha who let Foster use part of his own house for the pendulum experiments.
Split into simpler sentences: He took the island as the point of junction of his double line of longitudes setting out his survey. He was given considerable assistance by the Governor of Fernando Noronha who let Foster use part of his own house for the pendulum experiments.