"So much for the theory and principle of the wireless," resumed the doctor. "Of course I've only scratched the surface, and if I talked to you all night there'd be still lots left to say. But we only need to know a little about it to put it to practical use. And it is the practical use of the wireless telephone that I'm especially interested in for the sake of you boys. I'm satisfied that there's hardly anything that could give you more pleasure or more benefit than for each of you to have one of these contrivances in your own home. It's a wonderful educator, it helps to develop your interest in science, and what will perhaps appeal to you most of all, you can have more fun with it than anything else I know of."
Here Bob put in a question that was in the minds of many of the others.
"Does it cost very much, Doctor?" he asked.
"Not very much," the doctor replied. "Of course, some of the more powerful ones with vacuum tubes and other high class improvements run into the hundreds of dollars. But some very good receiving sets—and that's all you could use at the start, for it takes considerable time and you have to get a license before you are permitted to transmit—cans be bought for from twenty-five to seventy-five dollars."
There was a little gasp at this, some of which was due to a feeling of disappointment. It seemed beyond the range of what they could save up from their pocket money, and while the parents of some of them were well to do, others came from simple and frugal homes where every dollar had to be carefully counted.
The doctor was quick to note the expression on many faces, and took pains at once to remove any feeling of discouragement.
"But don't let that bother you at all," he said, "for with a little thought and planning any one of you will be able to build a telephone receiving set for himself at hardly any cost at all. In fact, I'd much rather have you build one than buy one, for in that way you'll get an understanding of the whole thing that otherwise you might not get at all. You'd be surprised perhaps if I told you that this set here was built by me and I wouldn't exchange the experience I've had in putting it together for a good deal of money."
"But you knew how to do it," put in Joe, "while we don't know the first thing about it. We wouldn't know how to start, even, let alone finish one."
"I was coming to that," returned Dr. Dale, smiling. "As some of you know, I've fitted up a workshop in the barn behind this house where I do a good deal of tinkering in my spare hours. Now I'm going to ask you boys to come out there next Saturday and see me build a wireless receiving set from A to Z. You'll be surprised to see how much can be done with a few things that cost very little money and with a lot of things that don't cost any money at all. How about it, boys?"
It was almost with a whoop that the invitation was accepted by his eager hearers, and the minister smiled with gratification at their enthusiasm.