He devised a mark system that combined reform with reward and enabled convicts to earn their freedom after accruing a certain number of marks, or credits.
Ia merancang suatu sistem penilaian dengan poin, yakni memberi imbalan apabila narapidana berperilaku baik, serta memungkinkan para narapidana memperoleh kebebasan mereka setelah mengumpulkan sejumlah poin atau kredit.