Alice and her father had been invited, the next day, to Ralph's laboratory, as he wished to show them some of his latest discoveries. They found him sitting in front of his desk while he was engaged in dictating scientific data to thin air. "Ah!" said Alice, as she entered, "you are evidently using some of the methods of my kidnapper, since you seem to be dictating to an invisible secretary!" "Nothing so complicated," said Ralph. Ralph, who then welcomed them, denied the charge, and went on to explain to his party his new invention. "The evolution of letter-writing has been a slow and painful one. Our remote ancestors, many thousands of years ago, carved their letters in stone slabs. Later on, the more civilized Egyptians wrote their letters upon papyrus. Still later, upon the invention of paper and ink, communications and letters could be written much better and faster in that improved manner. Later still, the typewriter came into use. "All of these methods had one great drawback. It was possible to easily falsify such records. While there had been handwriting experts, it happened very frequently in olden times--too frequently, in fact--that a signature on such an important document as, for instance, a will, was forged, and it became a question for handwriting experts to decide whether the signature was genuine. But even the handwriting experts were not always right. "It has often occurred to me that it should be possible to use the human voice as its own document so that it could be preserved in a different manner than the phonographic method discovered in the 20th century. Of course, under that method it was possible for one to speak one's last will and testament, but it was a clumsy way and was rarely used on account of its high cost. Furthermore it was difficult to make copies of a talk. Then, too, the disc or cylinder upon which the phonographic records were made were very fragile, and could be broken, either accidentally or purposely. "The method you see me using is phonetic, and it is practically impossible to falsify such a record. Watch how the machine works." Ralph reseated himself at his desk and started to talk. Facing him on the desk was a machine of about the shape of an old-fashioned typewriter, except that there were no keys. There were a few dials and knobs and from the top of the cabinet a white sheet of paper slowly emerged as Ralph dictated. When he had finished, he pressed a button and the entire sheet was ejected. It was covered with queer-looking wave lines, similar to the lines made by a seismograph when recording earthquakes--queer little parallel lines with humps at the tops that increased from very short wave-like scrolls to long ones. The entire sheet was covered with these lines in indelible ink. Ralph showed Alice the page and went on explaining: