According to Jerome how can you identify old boatsman?

From the text:

I like to watch an old boatman rowing, especially one who has been hired by the hour. There is something so beautifully calm and restful about his method. It is so free from that fretful haste, that vehement striving, that is every day becoming more and more the bane of nineteenth-century life. He is not for ever straining himself to pass all the other boats. If another boat overtakes him and passes him it does not annoy him; as a matter of fact, they all do overtake him and pass him—all those that are going his way. This would trouble and irritate some people; the sublime equanimity of the hired boatman under the ordeal affords us a beautiful lesson against ambition and uppishness.