Should you, by accident, whilst tying the knots, give the wrong end to be pulled, a hard knot will be the consequence, and you will know when this has happened the instant you try to draw the left-hand end of the handkerchief shorter. You must, therefore, turn this mistake to the best advantage, by asking any one of the company to see how long it will take him to untie one knot, you counting the seconds. When he has untied the knot, your other knots will remain right as they were before. Having finished tying the knots, let the same person hold them, and tell him that as he took two minutes to untie one knot, he ought to allow you fourteen minutes to untie the seven; but as you do not wish to take any advantage, you will be satisfied with fourteen seconds. You may excite some laughter during the performance of this trick, by going to the owner of the handkerchief, and desiring him to assist you in pulling a knot, saying, that if the handkerchief is to be torn, it is only right that he should have a share of it; you may likewise say that he does not pull very hard, which will cause a laugh against him. THE INVISIBLE SPRINGS. Take two pieces of white cotton _cord_, precisely alike in length; double each of them separately, so that their ends meet; then tie them together very neatly, with a bit of fine cotton _thread_, at the part where they double (_i. e._ the middle). This must all be done beforehand. When you are about to exhibit the sleight, hand round two other pieces of cord, exactly similar in length and appearance to those which you have prepared, but not tied, and desire your company to examine them. You then return to your table, placing these cords at the edge, so that they fall (apparently accidentally) to the ground behind the table; stoop to pick them up, but take up the prepared ones instead, which you have previously placed there, and lay _them_ on the table. Having proceeded thus far, you take round for examination three ivory rings; those given to children when teething, and which may be bought at any of the toyshops, are the best for your purpose. When the rings have undergone a sufficient scrutiny, pass the prepared double cords through them, and give the two ends of one cord to one person to hold, and the two ends of the other to another. Do not let them pull hard, or the thread will break, and your trick be discovered. Request the two persons to approach each other, and desire each to give you one end of the cord which he holds, leaving to him the choice. You then say, that, to make all fast, you will tie these two ends together, which you do, bringing the knot down so as to touch the rings; and returning to each person the end of the cord next to him, you state that this trick is performed by the rule of contrary, and that when you desire them to pull hard, they are to slacken, and _vice versâ_, which is likely to create much laughter, as they are certain of making many mistakes at first.