Complex sentence: Gibbs received the major honors then possible for an academic scientist in the US: he was elected to the National Academy of Sciences in 1879 and was awarded the 1880 Rumford Prize from the American Academy of Arts and Sciences for his work on chemical thermodynamics.
Split into simpler sentences: Gibbs received the major honors then possible for an academic scientist in the US. He was elected to the National Academy of Sciences in 1879 and received the 1880 Rumford Prize from the American Academy of Arts and Sciences for his work on chemical thermodynamics.