i.e. held taut on the upright indices of two persons, A and B — the trick may be, so to speak, doubled, by giving a twist with A's right, or ulnar string, distal round B's index, which I here take to be the left index, and similarly round A's index. If then the indices be placed tip to tip, or, which is the same thing, if the loops of A's index be transferred by this movement to B's index, the disposition can be resolved by pulling the free loop on the radial side of B's index. We thus have a theoretical finger string-trick which will be found on examination to be the same as Dr. Cunnington's East African head string-trick referred to above. It resolves also by pulling out straight either of the strings which cross the palmar aspect of the index. Compare Fig. \Zb.
If the distal string of the radial loop which crosses the back of B's left index as fourth or distal dorsal string be pulled slant across the third dorsal index string a kind of hitch is formed not readily resolved by pulling the radial loop, while yielding easily to the pull of the palmar string. Pull the distal palmar string down (the index being conveniently held horizontal) till nearly of a length with the side loops. Pass half this new palmar loop through the ulnar loop from the ulnar side and then through the radial loop, grip the separated halves with index and mid finger, and we have precisely the final arrange- ment of strings of the gypsy finger string-trick (Fig. 17). Or, reversing the process, if we set up the gypsy trick, and get the pulling loop clear by dropping the right index hold, this loop may, by drawing the radial and ulnar loops, be itself drawn taut to B's index, and we have the string arrangement of the theoretical trick. Fig. 18^, merely modified by the fourth dorsal index string being pulled across the third.
All this depends upon the properties of a common hitch or double half-hitch ; and as I believe the latter underlies not only these but other tricks, as well as some string figures, it is convenient to give it here.
Place the loop over the left index held horizontal. Pass the radial string proximal to the ulnar, then in a distal direction, give it a turn towards you, making a loop of which the returned piece of string forms the upper Hmb ; hitch the near side of