"But," wrote Uncle John in the letter accompanying the paper, "now the real work has only begun. The Wizard knows that some carbonized material is what he needs, but he is sure that carbonized cotton thread is not the best thing. Now he is carbonizing everything he can lay his hands on--straw, tissue paper, soft paper, all kinds of cardboard, all kinds of threads, fish line, threads rubbed with tarred lampblack, fine threads plaited together in strands, cotton soaked in boiling tar, lamp wick, twine, tar and lampblack mixed, and many other materials that I can't remember. Why," finished Uncle John, "so far he has examined no fewer than six thousand different species of vegetable growth alone. Somebody said something to him the other day about his wonderful genius. 'Well,' modestly answered the great man, mopping his forehead with his handkerchief, 'genius, I think, is one per cent _in_spiration and ninety-nine per cent _per_spiration.'" In December there came into Dora's life the most happy and exciting experience of her childhood. The letter from Uncle John in November had ended with this paragraph: "I am looking forward to my visit to Maine next month, but I'm sorry to say it must be earlier and shorter than usual. I have an important engagement here for the twenty-fourth, and I'm planning to reach Maine on Saturday, the twentieth, spend Sunday with you, and leave there the twenty-second. But I have thought of a way of making my visit last longer and of giving you a new kind of Christmas present. That way is to take you back with me to Jersey and let you see what Christmas and New Year's in the neighborhood of New York are like. If you approve my new idea for Christmas, I want you to let me know at once." If any twelve-year-old child who lives fifty miles from a city and has never been farther from home than that city in her life is reading this, she will know how Dora felt at the prospect of such a Christmas journey, and she will understand, too, how Dora had her answer ready for the post office in less than an hour after she had read her letter. The only event of Dora's wonderful vacation that this story has a right to tell is her visit to Mr. Edison. It happened that in the _Herald_ Uncle John bought as the train was nearing New York, there was a long article describing the lighting system that Mr. Edison had put into successful operation at Menlo Park. "Interest is getting so great in the incandescent light," remarked Uncle John, "that I shouldn't wonder if Mr. Edison let the public see it in operation. If he does, you and I are going to Menlo Park." The prophecy was a true one. On New Year's Mr. Edison opened his grounds to the public, the railroad ran special trains, and over three thousand people visited Menlo Park. Here is the enthusiastic letter that Dora wrote next day to Maine: NEWARK, N. J. _Jan. 1, 1880_