"Who's there?" came the demand from the unseen person in the tree.

"I might ask you the same thing," was Ned's sharp retort, as he nursed his skinned and bruised fingers. "What are you doing up there?"

There was no answer, but a sound among the branches indicated that the person up the tree was coming down. In another moment a man leaped to the ground lightly and stood beside Ned. The lad observed that the stranger was clean shaven, except for a small moustache which curled up at the ends slightly.

"For all the world like a small edition of the Kaiser's," Ned described it afterward.

"What are you doing here?" demanded the man, and his voice had in it the ring of authority. It was this very quality that made Ned bristle up and "get on his ear," as he said later. The young clerk did not object to being spoken to authoritatively by those who had the right, but from a stranger it was different

"I might ask you the same thing," retorted Ned. "I have as much right here as you, I fancy, and I can climb trees, too, but I don't care to have my fingers stepped on," and he looked at the scarified members of his left hand.

"I beg your pardon. I'm sorry if I hurt you. I didn't mean to. And of course this is a public place, in a way, and you have a right here. I was just climbing the tree to--er--to get a fishing pole!"

Ned had all he could do to keep from laughing. The idea of getting a fishing pole from a gnarled and stunted pine struck him as being altogether novel and absurd. Yet it was not time to make fun of the man. The latter looked too serious for that.

"Rather a good view to be had from up where you were, eh?" asked Ned suggestively.

"A good view?" exclaimed the other. "I don't know what you mean!"

"Oh, then you didn't see anything," Ned went on. "Perhaps it's just as well. Are you fond of fishing?"

"Very. I have-- But I forget, I do not know you nor you me. Allow me to introduce myself. I am Mr. Walter Simpson, and I am here on a visit I just happened to walk out this way, and, seeing a small stream, thought I should like to fish. I usually carry lines and hooks, and all I needed was the pole. I was looking for it when I heard you, and--"

"I felt you!" interrupted Ned, with a short laugh. He told his own name, but that was all, and seemed about to pass on.

"Are there any locomotive shops around here?" asked Mr. Simpson.

"Locomotive shops?" queried Ned. "None that I know of. Why?"

"Well, I heard heavy machinery being used down there;" and he waved his hand toward Tom's shops, "and I thought--"

"Oh, you mean Shopton!" exclaimed Ned. "That's the Swift plant. No, they don't make locomotives, though they could if they wanted to, for they turn out airships, submarines, tunnel diggers, and I don't know what."

"Do they make munitions there--for the Allies?" asked Mr. Simpson, and there was an eager look on his face.

"No, I don't believe so," Ned answered; "though, in fact, I don't know enough of the place to be in a position to give you any information about it," he told the man, not deeming it wise to go into particulars.

Perhaps the man felt this, as he did not press for an answer.

The two stood looking at one another for some little time, and then the man, with a bow that had in it something of insolence, as well as politeness, turned and went down the path up which Ned had come.

The young bank clerk waited a little while, and then turned his attention to the tree which seemed to have suddenly assumed an importance altogether out of proportion to its size.

"Well, since I'm here I'll have a look up that tree," decided Ned.

Favoring his bruised hand, Ned essayed the ascent of the tree more successfully this time. As he rose up among the branches he found he could look down directly into the yard with the high fence about it. He Could see only a portion, good as his vantage point was, and that portion had in it a few workmen--nothing else.

"No elephants there," said Ned, with a smile, as he remembered Harry's excitement. "Still it's just as well for Tom to know that his place can be looked down on. I'll go and tell him."

As Ned descended the tree he caught a glimpse, off to one side among some bushes, of something moving.

"I wonder if that's my Simp friend, playing I spy?" mused Ned. "Guess I'd better have a look."

He worked his way carefully close to the spot where he had seen the movement. Proceeding then with more caution, watching each step and parting the bushes with a careful hand, Ned beheld what he expected.

There was the late occupant of the pine tree the man who had stepped on Ned's fingers, applying a small telescope to his eye and gazing in the direction of Tom Swift's home.

The man stood concealed in a screen of bushes with his back toward Ned, and seemed oblivious to his surroundings. He moved the glass to and fro, and seemed eagerly intent on discovering something.

"Though what he can see of Tom's place from there isn't much," mused Ned. "I've tried it myself, and I know; you have to be on an elevation to look down. Still it shows he's after something, all right. Guess I'll throw a little scare into him."

As yet, Ned believed himself unobserved, and that his presence was not suspected was proved a moment later when he shouted:

"Hey! What are you doing there?"

He had his eye on the partially concealed man, and the latter. as Ned said afterward, jumped fully two feet in the air, dropping his telescope as he did so, and turning to face the lad.

"Oh, it's you, is it?" he faltered.

"No one else;" and Ned grinned. "Looking for a good place to fish, I presume?"

Then, at least for once, the man's suave manner dropped from him as if it had been a mask. He bared his teeth in a snarl as he answered:

"Mind your own business!"

"Something I'd advise you also to do," replied Ned smoothly. "You can't see anything from there," he went on. "Better go back to the tree and--cut a fishing pole!"

With this parting shot Ned sauntered down the hill, and swung around to make his way toward Tom's home. He paid no further attention to the man, save to determine, by listening, that the fellow was searching among the bushes for the dropped telescope.

The young inventor was at home, taking a hasty lunch which Mrs. Baggert had set out for him, the while he poured over some blueprint drawings that, to Ned's unaccustomed eyes,; looked like the mazes of some intricate puzzle.

"Well, where have you been keeping yourself, old man?" asked Tom Swift, after he had greeted his friend.

"I might ask the same of you," retorted Ned, with a smile. "I've been trying to find you to give you some important information, and I made up my mind, after what happened to- day, to write it and leave it for you if I didn't see you."

"What happened to-day?" asked Tom, and there was a serious look on his face.

"You are being spied upon--at least, that part of your works enclosed in the new fence is," replied Ned.

"You don't mean it!" Cried Tom. "This accounts for some of it, then."

"For some of what?" asked Ned.

"For some of the actions of that Blakeson, He's been hanging around here, I understand, asking too many questions about things that I'm trying to keep secret--even from my best friends," and as Tom said this Ned fancied there was a note of regret in his voice.

"Yes, you are keeping some things secret, Tom," said Ned, determined "to take the bull by the horns," as it were.

"I'm sorry, but it has to be," went on Tom. "In a little while

"Oh, don't think that I'm at all anxious to know things!" broke in Ned. "I was thinking of some one else, Tom--another of your friends."

"Do you mean Mary?"

Ned nodded.

"She feels rather keenly your lack of explanations," went on the young bank clerk. "If you could only give her a hint

"I'm sorry, but it can't be done," and Tom spoke firmly. "But you haven't told me all that happened. You say I am being spied upon."

"Yes," and Ned related what had taken place in the tree.

"Whew!" whistled Tom. "That's going some with a vengeance! I must have that tree down in a jiffy. I didn't imagine there was a spot where the yard could be overlooked. But I evidently skipped that tree. Fortunately it's on land owned by a concern with which I have some connection, and I can have it chopped down without any trouble. Much obliged to you, Ned. I shan't forget this in a hurry. I'll go right away and--"

Tom's further remark was interrupted by the hurried entrance of Eradicate Sampson. The old man was smiling in pleased anticipation, evidently, at the same time, trying hard not to give way to too much emotion.

"I's done it, Massa Tom!" he cried exultingly.

"Done what?" asked the young inventor. "I hope you and Koku haven't had another row."

"No, sah! I don't want nuffin t' do wif dat ornery, low- down white trash! But I's gone an' done whut I said I'd do!"

"What's that, Rad? Come on, tell us! Don't keep us in suspense."

"I's done some deteckertiff wuk, lest laik I said I'd do, an' I's cotched him! By golly, Massa Tom! I's cotched him black-handed, as it says!"

"Caught him? Whom have you caught, Rad?" cried Tom. "Do you suppose he means he's caught the man you saw up the tree, Ned? The man you think is a German spy?"

"It couldn't be. I left him only a little while ago hunting for his telescope."

"Then whom have you caught, Rad?" cried Tom. "Come on, I'll give you credit for it. Tell us!"

"I's cotched dat Dutch Sauerkrauter, dat's who I's cotched, Massa Tom! By golly, l's cotched him!"

"But who, Rad? Who is he?"

"I don't know his name, Massa Tom, but he's a Sauerkrauter, all right. Dat's whut he eats for lunch, an' dat's why I calls him dat. I's cotched him, an' he's locked up in de stable wif mah mule Boomerang. An' ef he tries t' git out Boomerang'll jest natchully kick him into little pieces--dat's whut Boomerang will do, by golly!"