Conversation so far:
When did William Thomson, 1st Baron Kelvin attend Cambridge?
William's father was able to make a generous provision for his favourite son's education and, in 1841, installed him, with extensive letters of introduction and ample accommodation, at Peterhouse, Cambridge.

Question: What did he study there?
Self-contained rewrite: What did William Thomson, 1st Baron Kelvin study at Peterhouse, Cambridge?