"No; but you are soiling a clean tablecloth. Pencil-marks are so
hard to get out. Take a piece of paper, please."

"Oh, is that all?" rejoined Mr. Swift with a smile. "Well, Tom, here
is the way I would do that," and substituting the back of an
envelope for the tablecloth, he continued the drawing.

Tom was looking over his father's shoulder interestedly, when Mrs.
Baggert, who was taking off some of the dinner dishes, suddenly
asked:

"Are you expecting a visitor, Mr. Swift?"

"A visitor? No. Why?" asked the inventor quickly.

"Because I just saw a man going in the machine shop," went on the
housekeeper.

"A man! In the machine shop!" exclaimed Tom, rising from his chair.
Mr. Swift also got up, and the two hurried from the house. As they
reached the yard they saw a man emerging from the building where Mr.
Swift was constructing his turbine motor. The man had his back
turned toward them and seemed to be sneaking around, as though
desirous of escaping observation.

"What do you want?" called Mr. Swift.

The man turned quickly. At the sight of Mr. Swift and Tom he made a
jump to one side and got behind a big packing-box.