One day recently, when I found him less confident than usual as to the triumph of the phonograph in the near future, he said: "There are some difficulties about the problem that seem insurmountable. I go on smoothly until at a certain point I run my head against a stone wall; I cannot get under, over, or around it. After butting my head against that wall until it aches, I go back to the beginning again. It is absurd to say that because I can see no possible solution of the problem to-day, that I may not see one to-morrow. The very fact that this century has accomplished so much in the way of invention, makes it more than probable that the next century will do far greater things. We ought to be ashamed of ourselves if we are content to fold our hands and say that the telegraph, telephone, steam-engine, dynamo, and camera having been invented, the field has been exhausted. These inventions are so many wonderful tools with which we ought to accomplish far greater wonders. Unless the coming generations are particularly lazy, the world ought to possess in 1993 a dozen marvels of the usefulness of the steam-engine and dynamo. The next step in advance will perhaps be the discovery of a method for transforming heat directly into electricity. That will revolutionize modern life by making heat, power, and light almost as cheap as air. Inventors are already feeling their way toward this wonder. I have gone far enough on that road to know that there are several stone walls ahead. But the problem is one of the most fascinating in view." X. ALEXANDER GRAHAM BELL. [Illustration: Professor Bell Sending the First Message, by Long-distance Telephone, from New York to Chicago.]