Modern Magic: A Practical Treatise on the Art of Conjuring

You take care not to bring on the goblet and cover until you have, by substitution, gained possession of the two marked coins which you have borrowed for the purpose of the trick. Retiring to fetch the glass and cover, you prepare the latter by inserting the marked coins. This you do by holding the cover upside down, pressing the knob (thus drawing back the spring slide), and dropping the coins into their receptacle. On removing the pressure on the knob, the slide returns to its normal position. You then bring forward the goblet and cover, and place them on the table. Holding the goblet upside down, to show that it is empty, you place the cover over it, ostensibly to prevent anything being secretly passed into it, and, for still greater security, throw a handkerchief, borrowed for that purpose, over the whole. You now announce that, notwithstanding the difficulties which you have voluntarily placed in the way, you will pass the two marked coins through the handkerchief, and through the metal cover into the glass. Taking in your right hand one of the substitutes, which have all along remained in sight, and which the audience take to be the genuine coins, you pretend by Pass 1 to transfer it to your left, and pressing gently on the knob with the last-mentioned hand, cause one of the marked coins to drop from the cover, at the same moment opening the hand to show that the coin has left it.