every island once, and once only, finishing up his tour at the starting-point A. But he always put off his visit to C as long as possible, for trade reasons that I need not enter into.  The puzzle is to discover his exact route, and this can be done with certainty.  Take your pencil and, starting at A, try to trace it out.  If you write down the islands in the order in which you visit them—­thus, for example, A, I, O, L, G, etc.—­you can at once see if you have visited an island twice or omitted any.  Of course, the crossings of the lines must be ignored—­that is, you must continue your route direct, and you are not allowed to switch off at a crossing and proceed in another direction.  There is no trick of this kind in the puzzle.  The sailor knew the best route.  Can you find it?

[Illustration]

250.—­THE GRAND TOUR.

One of the everyday puzzles of life is the working out of routes.  If you are taking a holiday on your bicycle, or a motor tour, there always arises the question of how you are to make the best of your time and other resources.  You have determined to get as far as some particular place, to include visits to such-and-such a town, to try to see something of special interest elsewhere, and perhaps to try to look up an old friend at a spot that will not take you much out of your way.  Then you have to plan your route so as to avoid bad roads, uninteresting country, and, if possible, the necessity of a return by the same way that you went.  With a map before you, the interesting puzzle is attacked and solved.  I will present a little poser based on these lines.

I give a rough map of a country—­it is not necessary to say what particular country—­the circles representing towns and the dotted lines the railways connecting them.  Now there lived in the town marked A a man who was born there, and during the whole of his life had never once left his native place.  From his youth upwards he had been very industrious, sticking incessantly to his trade, and had no desire whatever to roam abroad.  However, on attaining his fiftieth birthday he decided to see something of his country, and especially to pay a visit to a very old friend living at the town marked Z. What he proposed was this:  that he would start from his home, enter every town once and only once, and finish his journey at Z. As he made up his mind to perform this grand tour by rail only, he found it rather a puzzle to work out his route, but he at length succeeded in doing so.  How did he manage it?  Do not forget that every town has to be visited once, and not more than once.

[Illustration]

251.—­WATER, GAS, AND ELECTRICITY.