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--
can 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