Willam Jones, scientist with a Welsh connection!
Willam JonesA brilliant linguist William studied and eventually related the Indo European language family which connects Greek, Latin and even Welsh! He also met with Ben Franklin to discuss a peaceful settlement in the American War of Independence.
Connection: Son of Sir William Jones the great Welsh matamatician from Llanfihangel. He was actually born in London.
He was also juge in wales and at one point was tutor to earl spensor, an ancestor of Diana, Princess of Wales.