Sidenote: That's a really weird way of writing his first name. While the Russian does have a letter that visually resembles ë (unicode: ё), it is not a variation of the letter e as this transcription suggests, but invariably pronounced something like 'yo'. The name is pronounced "Pyotr", and of course corresponds to Peter, by which name Kropotkin was also known. I've no idea where this spelling comes from, but it's like writing Bladimir or Cergei instead Vladimir Sergey. Weird.
PS: Read Kropotkin, he's good.