On chapter 29 What does Jarvis give to Harrison? What's the significance of it?

Jarvis bids farewell to Harrison and his son. Harrison tells Jarvis that the Court made a mess of the case, and that they should have hammered away at Mkize. Jarvis gives John Harrison an envelope to open when he is gone. John Harrison reads it later: it requests that John do all the things that Arthur wanted to do at what could be called the Arthur Jarvis club, and includes a check for ten thousand dollars.