Jupe’s summons to supper ended the talk for the time being, and the two lads went below to eat a hearty meal while the colored man took a spell at the wheel. After supper they emerged on deck again, and as Jack took the helm Tom drew up a camp stool beside him, and seating himself, spread the figure-covered sheet of paper out on the chart case. He then switched on the shaded light, which caused a soft glow to reveal the cabalistic scribbling clearly. “Now then,” he began, “in figuring out a cipher of this sort the first thing to do is to note what figure appears most frequently. Having ascertained this, it is safe to assume that such a figure stands for the most frequently occurring letter in the language,—always provided, of course, the message is in English.” “Well?” interrogated Jack. “We know that the most frequently used vowel in English is _E_. And, by the way, this translation proved fairly easy, because the transmitter of the message made a gap between each of his groups of figures, showing that each collection stood for a separate word.” “I noticed that,—go ahead.” “I was trying to show you something of the method; but I guess you’ve about grasped it. In figuring out the cipher I made groups of all the numerals occurring in your transcript of the message, and found that the number ‘five’ appeared most often. I assumed, then, that it stood for H. Working in this way, I found that the first word of the message was _The_. That _Th_ stuck for some time, till I saw that the figures ‘twenty-five’ had been used to express the phonetic sound of _Th_. “This gave me a valuable clew. I wrote down _The_ and then passed on to the next words. Figuring as before, I assigned the number ‘three,’ which appeared alone, to the letter _C_. I was puzzled for a minute. ‘_The C_’ didn’t seem to mean a whole lot, but I let it go and passed on to the next word. Using my system I spelled out _King_, and then, of course, I realized that the _C_ was a phonetic rendering for the first part of the yacht _Sea King’s_ name.” “Great guns!” gasped Jack, “then they are interested in dad’s craft and——” “Wait a while; let me get the rest of it off my chest. I’m not going to tire your patience out by going through every step. I’ve told you enough to show you my method. As I got further combinations it became more and more simple till I finally had this message figured out: “‘The _Sea King_ is disabled. Trying to get bearings from you know who. _Vagrant_ left Lone Island this P. M. going to rescue. You had better make all speed or they will beat you out. Am proceeding. X. Y. Z.’” Jack’s lips emitted an amazed whistle. “What sort of a maze have we blundered into?” he exclaimed. “This X. Y. Z., who is he? Who was he talking to? What are they after?”