Rudolf Clausius played an important role in the founding of thermodynamics. Some years ago, I looked through one of his textbooks on thermodynamics from the 1860s. His textbooks on thermodynamics went through several editions and some (at least) of the editions were translated into English. They have a modern looking presentation and seem familiar, perhaps or probably because some modern text books on thermodynamics are modeled on his wonderful textbooks.
There is an article about him in Wikipedia. There is a chapter about him Great Physicists by William Cropper (2004). There was an obituary in 1888, the year he died, in PNAS vol 24. Are there any other sources?