Georges-Louis Leclerc, Comte de Buffon (1707 - 1788) was a French naturalist who attempted to synthesize all existing knowledge on geology, botany, zoology, paleontology, history and anthropology in one monumental work, his Histoire naturelle. He wrote 36 of his planned 50 volumes before his death.
He was also a mathematician who posed interesting problems in probability theory - one that is used for math students today is called Buffon's Needle. Buffon translated Sir Issac Newton's works into French. He was the head of the botanical gardens and zoo in Paris, the Jardin du Roi (now the Jardin des Plantes). He estimated the age of the Earth at 75,000 years -- one of the first to approach this question with a scientific method rather than calculating the Earth's age using the Bible.
When I first read about Leclerc (as many geology texts refer to him) I realized with amusement that he was the "Buffon" that Doctor Dolittle refers to, when he wants to look up the pushmi-pullyu in the jungles of Africa.