all this leads us back to vacuum tubes, for it’s only with them that all these things would be possible. Perhaps in the future something better yet will be invented, but they’re the best we have at present. I’m heartily in favor of you boys using a tube instead of a crystal, because it will give you vastly more enjoyment in your work. I wouldn’t have more than one at the start, but later on it may be well to have more. I have a catalogue up at my house of the various makes and prices, and if you’ll run up there any time I’ll give it to you. At the same time I’ll show you just how it’s got to be inserted and attached. Maybe also I’ll be able to help you in the making of the horn. I’ll have to go now,” he added, looking at his watch. “It’s surprising how the time flies when we get on this subject. Good-bye, boys, and don’t forget to drop in at the house whenever you can.”
