Latitude by Nicholas Crane

The year is 1735. Twelve unruly men board ships bound for South America. Their mission? To discover the true shape of the Earth. They will be exposed to a wilderness of dangers none can imagine. The survivors won’t return for ten years.” (taken from the back cover of the book)

I can thoroughly recommend this books which puts into story form the epic journey of French and Spanish scientists to Ecuador to measure the equator and 2 degrees of latitude south of the equator, and thus determine whether the earth bulges at the equator or at the poles.