t Tom. "He must have been talking. That isn't
like him. I must look into this."

Then to his caller he said:

"Really, you must excuse me, Mr. Boylan, but I don't care to do
any business with Mr. Peters. Tell him, with my thanks, that there
is really nothing doing in his line. I prefer to exploit my own
inventions."

"That is your last word?"

"Yes," returned Tom, as he gathered up the drawings.

"Well," said Mr. Boylan, and Tom could not help thinking there was
a veiled threat in his tones, "you will regret this. You will be
sorry for not having accepted this offer."

"I think not," replied Tom, confidently. "Good-day."

The young inventor sat for some time thinking deeply, when his
visitor had gone. He called Eradicate to him, and gently
questioned the old colored man, for Eradicate was ageing fast of
late, and Tom did not want him to feel badly.

It developed that the servant had been closely cross-questioned by
Mr. Boylan, while he was waiting for Tom, and it was small wonder
that the old colored man had let slip a reference to the photo
telephone. But he really knew nothing of the details of the
invention, so he could have given out no secrets.

"But at the same time," mused Tom, "I must be on guard against
these fellows. That Boylan seems a pretty slick sort of a chap. As
for Peters, he's a big 'bluff,' to be perfectly frank. I'm glad I
had Mr. Damon's warning in mind, or I might have been tempted to
do business with him."

"Now to get busy at this photo telephone again. I'm going to try a
totally different system of transmission. I'll use an alternating
current on the third wire, and see if that makes it any better.
And I'll put in the most sensitive selenium plate I can make. I'm
going to have this thing a success."

Tom carefully examined the drawings of his invention, at which
papers Mr. Boylan had confessed to looking. As far as the young
inventor could tell none was missing, and as they were not
completed it would be hard work for anyone not familiar with them
to have gotten any of Tom's ideas.

"But at the same time I'm going to be on my guard," mused Tom.
"And now for another trial."

Tom Swift worked hard during the following week, and so closely
did he stick to his home and workshop that he did not even pay a
visit to Mr. Damon, so he did not learn in what condition that
gentleman's affairs were. Tom even denied himself to his chum Ned,
so taken up was the young inventor with working o