the upper figures, in ordinary type, expressing the numbers of the pages, and the lower, in black type, the corresponding key numbers, a very small amount of study will associate them so closely in the mind as to fix them firmly in the memory.

Having mastered these two simple lessons, the learner is in a position to use the pocket-book. To ascertain the card chosen, he has only to add together the key numbers of the pages in which he is told that such card appears. The total will be the number at which that card stands in the list given on [page 185], and, this being known, it becomes an easy matter to name the card itself.

We will suppose, for instance, that performer is told that the chosen card appears on the second page, and no other. The key number of this page being 2, the card must be the second in the list, viz., the deuce of clubs. If he is told that the chosen card is to be found on pages 1, 3 and 6: the key number of these three pages being 1, 4 and 32: together making 37, and thirty-seven less twenty-six being eleven, he knows that the card must be the eleventh of the third suit, otherwise the knave of spades. If he is told that the card is on the third, fifth and sixth pages, the key numbers of which are 4, 16 and 32, total 52, it is clear that the card must be the last in the list, viz., the king of diamonds.

So much for the working of the trick. But the reader, if of an enquiring mind, will naturally ask, “How is this result obtained?” The answer rests upon a special property of the geometrical progression which forms the six key numbers. It is a curious fact that by the use of these six numbers, either singly or in combination with others of the series, any number, from unity up to 63, can be expressed. Thus, the numbers, 1, 2, 4, 8, 16 and 32 we already have, these being numbers of the series. As to other numbers:

and so on throughout up to 52, which being the limit of the pack, is the highest number with which we need concern ourselves.

In making up the pages of the pocket-book, advantage has been taken of this principle. A given card is inserted on that page or pages (and those only) whose key numbers, alone or added together, correspond with the position which the card holds in the list. Thus the ace of clubs will appear on the first page (not because it is the first card, but because the key number of that page is 1) and on no other. The deuce of clubs, in like manner, on page 2, the key number of that card being two. The next card, the three of clubs, must appear on page 1 and page 2, their key numbers together amounting to 3. The process as to cards standing at higher numbers is the same. Thus, the ace of spades, being the twenty-seventh card, and twenty-seven being the aggregate of 16, 8, 2 and 1, will appear on the first, second, fourth and fifth pages. Conversely, if the performer is told that the card appears on the four pages last named, he knows that it is the twenty-seventh card, i.e., the ace of spades. Any spaces remaining vacant on the page after the whole pack has been dealt with, are filled up by duplicates of cards already figuring on the same page, their appearing under these conditions making no difference to the calculation.

I am indebted to an ingenious amateur, Mr. Victor Farrelly, for the idea of a novel method of using the pocket-book. Mr. Farrelly does not offer of his own accord to show what can be done with it, but keeps it in reserve, for use in a special emergency. Every conjurer meets now and then with the pig-headed person who absolutely declines to have a given card forced upon him, and persists in endeavouring to extract one from some other part of the pack. Armed with the pocket-book, the performer can set such a person at defiance, and indeed get additional kudos from his objectionable behaviour.