"During his absence, put the third knife into the fire…"
This is a diversion from The Young Man’s Book of Amusement, a Victorian book that I surmise would have been extremely popular among certain types of young men. For example, it contained instructions for making and inhaling laughing gas, giving you this helpful advice:
"The sensations produced by breathing this gas, are not the same in all persons, but they are always of an agreeable nature, and not followed by any depression of spirits, like those occasioned by fermented liquors."
The book contains tricks, pranks and dangerous science experiments involving electricity, various acids and fireworks.
Here’s a practical joke to deceive a person with three knives (because it’s always a good idea to pull a joke on someone while they’re holding a knife.)
The Three Knives.
Wager any sum with a person that you will give him three knives to hide, one after the other, and will tell him where he deposits the last. He will doubtless stipulate that he shall be permitted to hide them out of the room. This you readily agree to, and on presenting him with the first and second knives, he will go out and carefully deposit them in some secret hole or corner. During his absence, put the third knife into the fire, so that it will be moderately heated by the time he is prepared to receive it. As soon as he takes hold of it, he will very naturally deposit it upon the floor, with sundry ejaculations incidental to the touching any thing too hot to hold. You then say, " There it is, you have deposited the last upon the floor, and I have won the wager." This trick generally causes much laughter.
The Young Man’s Book of Amusement containing the most interesting and instructive experiments in various branches of science to which is added all the popular tricks and changes in cards and the art of making fireworks, 1854>>