Kendall: You don't read carefully, do you?

George Frederick Root
Nicholas de Giers
John Henry Brown
Frederich Engels
all lived from 1820 to 1895.

I haven't identified Augustus Morris and John Sharpe, but I imagine Rapparee has determined that they lived from 1820 to 1895, and that's why he suggested them.

However, Wikipedia has pictures of the first 4, and I think they can all be eliminated based on their looks. See if you agree.