Though it was still only eleven o'clock, the boys were quite ready for dinner when they reached the lake; and when it was finished and they had hidden the rest of their provisions in some bushes, Herr Groos gave them leave to amuse themselves as best they chose till he sounded his horn to collect them for another meal at four o'clock. He himself was going to take charge of a botanising party on the Hersch-felsen, and a junior master was to superintend those who wished to fish in the lake; but Franz decided to join neither party, as his one idea was to catch a swallow-tailed butterfly for his friend. At last, finding no one with a similar ambition, he started on his quest alone.

'I will try the KÜhberg first,' he said to himself. 'If we should meet the strangers again, it would be fun to prove to them that Herr Groos was right and they were wrong.'

It was very hot as Franz toiled up the mountain-side, and when at last he reached the place where his search was to begin, he lay down panting under some trees at the edge of the wood. On the opposite slope he could see the yellow caps of his comrades, and the tall figure of Herr Groos; but where he himself was all was solitude and silence. After a few minutes' rest he rose, and having filled his cap with some delicious berries, sat down, almost buried amongst the cool, green plants, to enjoy them. They were soon finished, but he was still too lazy to move, and rolling himself down till the cranberries nearly met above him, he fell fast asleep.

He was awakened by the sound of voices, and, thinking it was some of his schoolfellows, he lay still, meaning to surprise them. He was so well hidden that he knew he could not be discovered unless he moved. Then he realised that it was not his comrades, but the two strangers from the train.

'Look at all those boys over there,' said the tall man. 'It was fortunate that we put them off the scent. If they had chosen to spend the day up here it would have upset our plans nicely.'

'Are you sure, though, that they are all there?' asked the other, doubtfully. 'There were thirty-two in the train, and I can only count twenty-five yellow caps now.'

'You are right, Schmidt,' answered the tall man, after a short pause. 'And who can tell where the others may be?'

'Not I! We must put off our digging till we are sure that they have all gone away for the night.'

'We shall miss the American boat,' said his friend, angrily, 'and all because of a pack of schoolboys!'

'Not necessarily. If we return to Freistadt by the nine o'clock train instead of by the five o'clock, we ought still to catch the steamer at Hamburg. That is the worst of taking things from a well-known man like Rosenthal. He makes it unsafe to dispose of a single recognisable thing in Germany. We were lucky to get rid of the coins, even.'

'And a mere nothing we got for them,' replied the grumbler. 'Are you certain you remember where we buried the rest of the collection?'

'Under this stone here, by the big tree, and it has evidently never been moved since we left it. See, the cranberries are already beginning to grow round it.'

'Which shall we take this time? I wish we could get the stuff all sold and done with!'

'So do I! but we cannot take too much to one country. If we make a good haul in America, we will return, and try and see what we can do in England with the rest.'

'If we cannot dig now, what are we to do?' asked the tall man, disgustedly.

'We must go on to the Observatory, and pass the time there. There is nothing else to be done.'

When they had quite gone, Franz raised himself slowly. There was the great stone, just as the short man had said, and underneath it were evidently most of the treasures stolen from Baron Rosenthal. What was the best thing to do? If he dug the treasures up and hid them elsewhere, they would be safe, but then the thieves would probably escape. If he went straight back to Freistadt by train and warned the police, Herr Groos would think he was lost, and there would be such a hue and cry in the woods that the strangers would probably hear of it and have their suspicions aroused.

Then an inspiration came to him. He would telegraph to Hugo in cypher, and then, even if Baron Rosenthal himself were not there, Hugo would have the sense to arrange matters. It took him some time to concoct his telegram, and put it into cypher. It ran as follows:—

'A tall man in grey and a shorter man in brown, with butterfly nets and big specimen cases, will reach Freistadt station at ten-thirty. Have them arrested, as their cases contain some of your father's silver, and the rest is hidden in the woods.—Franz.'

Visitors were always allowed to use the telegraph at the Observatory on the top of the hill, and so he decided to go there at once and send off his message. Then a fresh danger occurred to him. The two strangers were going to the little inn by the Observatory. If they chanced to see his telegram, or even asked to look at it, he would arouse their suspicions if he declined to show it, and yet, if the short stranger were as clever as he professed to be, he would probably decipher it and learn everything. So he wrote a companion message, using some of the same words and figures as in the cypher one, but arranging them so that they could not possibly be translated to make sense.

When he arrived at the top of the hill, he found the two strangers, as he had expected, sitting at a little table outside the building.

'Hallo, youngster, have you caught your swallow-tail yet?' inquired the tall one.

'I have not even seen one,' replied Franz, truthfully. 'I am afraid they have all left the Hirsch-felsen since you were there. I gave it up at last and came on here to send a cypher telegram to my friend.'

'Ah! the cypher!' said the fat man. 'Show me what you are going to say, and I will warrant myself to read it.'

'Very well, but be quick, for I want to send it off,' replied Franz, seeing that this would disarm suspicion.

He gave the strangers the copy he had specially prepared for them, and, to his surprise, the stout man did manage to read it, though, naturally, he thought nothing of its contents. Then Franz took the real telegram to the clerk at the Observatory, who dispatched it carefully, though he chaffed Franz a good deal about the enormous importance of a message that required to be sent so secretly.

When he rejoined his companions by the lake, just in time for the afternoon meal, he was well teased by them because he was the only boy who had no important find to announce. Then followed a merry walk back through the woods, then supper, and then bed, and through it all Franz never had a chance of a private talk with Herr Groos.

The next morning the boys were still at breakfast when the early morning train came creaking into the station, and the first person to come towards the inn was Baron Rosenthal.

He shook Franz warmly by the hand. 'Thanks to you, my boy,' he said, 'the thieves are in prison. It only remains for you to show us where the rest of the silver is hidden.'

The other boys gazed at Franz in surprise, but he was not long in telling the whole story, and explaining how it was that he had been the only boy who had had no time to collect specimens. Half an hour later the whole party started for the KÜhberg, with Franz to guide them.

Afterwards, when the winter came, and the boys of the class discussed the great summer excursion, they always agreed that the most exciting part of it had been the digging for Baron Rosenthal's treasures under the pine tree. Not a few of them also, though without success, tried to invent a cypher that should rival the famous one which had proved of such real and unexpected value.

A. Katharine Parkes.