The narrator is getting relief from his business life by gazing at the river from the Thames Embankment, when someone who looks like a tramp starts a conversation with him. Despite his appearance he talks like an educated businessman. He has a bag of what look like uncut diamonds. One, which is as big as the tip of a thumb, he offers to sell for a hundred pounds, but the narrator is suspicious.
The man tells him that he has spent years on a project to make diamonds. It was done secretly, so that others would not copy his work, and so that he could sell his diamonds without it being known that they could be produced in large quantities. After his money ran out he conducted his experiments in cheap lodgings in Kentish Town, and had various menial jobs. Using an idea suggested by experiments of Gabriel Auguste Daubrée, he put the mixture which might produce diamonds together with dynamite in a cylinder too strong to burst, and he finally succeeded; but as he looked at the results a neighbour in the lodgings house, thinking he was a bomb-making anarchist, told him he had called the police. He abandoned the lodgings house, taking with him his diamonds; this left him in the state in which the narrator has found him: homeless and carrying diamonds which he cannot try to sell without causing suspicion.
The narrator thinks the man's story might be genuine, and gives him his business card, but although he had some communication with him for a period, he does not see the man again. Reflecting later on the encounter, he wonders if the man is dead, or will perhaps re-emerge and become famous; he wonders if he missed a business opportunity.
I have this same chapter in my book.(Pathways)
