"Enough to understand and to make myself understood," replied the girl. "Why?"
The Thinking Machine scribbled off a copy of the cipher and handed it to her.
"I'll communicate with you when I reach a conclusion," he remarked. "Please leave your address on your card here," and he handed her the card and pencil.
"You know my home address," she said. "Perhaps it would be better for me to call this afternoon late or to-morrow."
"I'd prefer to have your address," said the scientist. "As I say, I don't know when I shall be able to speak definitely."
The girl paused for a moment and tapped the blunt end of the pencil against her white teeth thoughtfully with her left hand. "As a matter of fact," she said at last, "I am not returning home now. The events of last night have shaken me considerably, and I am now on my way to Blank Rock, a little sea shore town where I shall remain for a few days. My address there will be the High Tower."
"Write it down, please!" directed The Thinking Machine tersely. The girl stared at him strangely, with a challenge in her eyes, then leaned over the table to write. Before the pencil had touched the card, however, she changed her mind and handed both to Hatch, with a smile.
"Please write it for me," she requested. "I write a wretched hand anyway, and besides I have on my gloves." She turned again to the little scientist, who stood squinting over her head. "Thank you so much for your trouble," she said in conclusion. "You can reach me at this address either by wire or letter for the next fortnight."
And a few minutes later she was gone. For awhile The Thinking Machine was silent as he again studied the faint writing on the strip of paper.
"The cipher," he remarked to Hatch at last, "is no cipher at all; it's so simple. But there are some other things I shall have to find out first, and-suppose you drop by early to-morrow to see me."
Half an hour later The Thinking Machine went to the telephone, and after running through the book called a number.
"Is Miss Harding home yet?" he demanded, when an answer came.
"No, sir," was the reply, in a woman's voice.
"Would you mind telling me, please, if she is left handed?"
"Why, no, sir. She's right handed. Who is this?"
"I knew it, of course. Good by."
The Thinking Machine was squinting into the inquiring eyes of Hutchinson Hatch.
"The reason why the police are so frequently unsuccessful in explaining the mysteries of crime," he remarked, "is not through lack of natural intelligence, or through lack of a birthgiven aptitude for the work, but through the lack of an absolutely accurate knowledge which is wide enough to enable them to proceed. Now here is a case in point. It starts with a cipher, goes into an intricate astronomical calculation, and from that into simple geometry. The difficulty with the detectives is not that they could not work out each of these as it was presented, perhaps with the aid of some outsider, but that they would not recognize the existence of the three phases of the problem in the first place.
"You have heard me say frequently, Mr. Hatch, that logic is inevitable-as inevitable as that two and two make four not sometimes, but all the time. That is true; but it must have an indisputable starting point,-the one unit which is unassailable. In this case unit produces unit in order, and the proper array of these units gives a coherent answer. Let me demonstrate briefly just what I mean.
"A masked woman, employing the method at least of a thief, demands a certain bracelet of this Miss-Miss Harding. (Is that her name?) She doesn't want jewels; she wants that bracelet. Whatever other conjectures may be advanced, the one dominant fact is that that bracelet, itself of little comparative value, is worth more than all the rest to her,-the masked woman, I mean,-and she has endangered liberty and perhaps life to get it. Why? The history of the bracelet as she herself stated it to Miss Harding gives the answer. A man in prison, under sentence of death, had that bracelet at one time. We can conjecture immediately, therefore, that the masked woman knew that the fact of its having been in this man's possession gave him an opportunity at least of so marking the bracelet,-or of confiding in it, I may say, a valuable secret. One's first thought, therefore, is of treasure-hidden treasure. We shall go further and say treasure hidden by a Continental officer to prevent its falling into other hands as loot. This officer under sentence of death, and therefore cut off from all communication with the outside, took a desperate means of communicating the location of the treasure to his heirs. That is clear, isn't it?"
The reporter nodded.
"I described the bracelet,-you heard me,-and yet I had never seen it, nor had I a description of it. That description was merely a forward step, a preliminary test of the truth of the first assumptions. I reasoned that the bracelet must be of a type which could be employed to carry a message safely past prying eyes; and there is really only one sort which is feasible, and that is the one I described. These bracelets are always hollow, the invisible hinges hold them together on one side, and they lock on the other. It would be perfectly possible, therefore, to write the message the prisoner wanted to send out on a strip of tissue paper, or any thin paper, and cram it into the bracelet at the lock end. In that event it would certainly pass minute inspection; the only difficulty would be for the outside person to find it. That was a chance; but it was all a chance anyway.
"When the young woman came here and produced a strip of thin paper, apparently blank, with the multitude of wrinkles in it, I immediately saw that that paper had been recovered from the bracelet. It was old, yellow, and worn. Therefore, blank or not, that was the message which the prisoner had sent out. You saw me hold it over the brazier, and saw the characters appear. It was sympathetic ink, of course.
"Hard to make in prison, you say? Not at all. Writing either with lemon juice or milk, once dry, is perfectly invisible on paper; but when exposed to heat at any time afterward, it will appear. That is a chemical truth.
"Now the thing that appeared was a cipher-an absurd one, still a cipher. Extraordinary precaution of the prisoner who was about to die! This cipher-let me see exactly," and the scientist spelled it out:
" 'Stonehedge-idim-serpa'l ed serueh siort tnaeG ed eteT al rap eetej erbmo'l ed tniop ud zerit sruO'd rehcoR ud eueuq ud dron ua sdeip tnec.'
"If you know anything of languages, Mr. Hatch," he continued, "you know that French is the only language where the apostrophe and the accent marks play a very important part. A moment's study of this particular cipher therefore convinced me that it was in French. I tried the simple expedient of reading it backward, with this result:
" 'Stonehedge. Cent pieds au nord du queue du Rocher d'Ours tirez du point de l'ombre jetee par La Tete de Geant trois heures de l'apres-midi.'
"Here, therefore, was a sensible statement in French, which translated freely into English is simply:
'Stonehedge. Hundred feet due north from tail Bear Rock through apex (or point) of shadow cast by Giant's Head, three p.m.'
"I had read the cipher and knew its English before I gave a copy of it to the young woman who was here. I specifically asked her if she knew French, to give her a clue by which she might interpret the cipher herself. And thus I blazed the way within a few minutes to the point where astronomical and geometrical calculations were next. Please bear in mind that this message from the dead was not dated.
"Now, about the young woman herself," continued the scientist after a moment. "The statement of how she came to find the bracelet was obviously untrue; particularly are we convinced of this when she cannot, or will not, explain how it was broken. Therefore, another field is open for scrutiny. The bracelet was broken. If we assume that it is the bracelet, and there is no reason to doubt it, and we know it is in her possession, we know also that more than one person had been searching for it. We know positively that that other person-not the masked girl, but the one who had preceded her to Miss Harding's room on the same night-got the bracelet from Miss Harding, and we are safe in assuming that it passed out of that other person's hand by force. The bracelet had been literally torn apart at the hinge. In other words, there had been a physical contest, and one piece of the circlet-the piece with the message-passed out of the hands of the person who had preceded the masked woman and stolen the bracelet.
"But this is by the way. Stonehedge is the name of the old Tremaine Harding estate, about twenty miles out, and there the Tremaine Harding family valuables were hidden by William Tremaine Harding, who died by bullet, a martyr to the cause of freedom. We shall get the treasure this afternoon, after I have settled one or two dates and made the astronomical and geometrical calculations which are necessary."
There was silence for a minute or more, broken at last by the impatient "Honk, honk!" of an automobile outside.
"We'll go now," announced The Thinking Machine as he arose. "There is a car for us."
He led the way out, Hatch following. A heavy touring car, with three seats, driven by a young woman, was waiting at the door. The woman was a stranger to the reporter; but there was no introduction.
"Did you get the date of Captain Harding's imprisonment?" asked The Thinking Machine.
"Yes," was the reply,-"June 3, 1776."
The Thinking Machine clambered in, Hatch following silently, and the car rushed away. It paused in a suburb long enough to pick up two workmen with picks and shovels, who took their places in the back seat, and then the automobile with its strange company-a pretty woman, a newspaper reporter, a distinguished scientist, and two laborers-proceeded on its way. Hatch, alone in the second seat, heard only one remark by the scientist, and this was:
"Of course she was clever enough to read the cipher, after I gave her the hint that it was in French; so we shall find that the place has been dug over; but there is only one chance in three hundred and sixty-five that the treasure was found. I give her credit for extraordinary cleverness; but not enough to make the necessary astronomical calculations."
A run of an hour and a half brought them to Stonehedge, a huge old estate with ramshackle dwelling and acres of rock ridden ground. Away off in the northwest corner were two large stones-Bear Rock and Giants Head-rising fifteen or twenty feet above the ground. The car was driven over a rough road and stopped near them.
"You see, she did read the cipher," remarked the scientist placidly. "Workmen have already been here."
Straight ahead of them was an excavation ten feet or more square. Hatch peered into it, while The Thinking Machine busied himself by planting a stake at the so-called tail of Bear Rock. Then he glanced at his watch,-it was half past two o'clock,-and sat down with the young woman in the shadow of Giants Head. Hatch lounged on the ground near them, and the workmen made themselves comfortable in their own way.
"We can't do anything till three o'clock," remarked The Thinking Machine.
"And just what shall we do then?" inquired the young woman expectantly. It was the first time she had spoken since they started.
"It is rather difficult to explain," said The Thinking Machine. "The hole there proves that the young woman read the cipher, of course. Now here briefly is why the treasure was not found. To-day is September 17. A measurement was made, according to instructions, from the tail of Bear Rock through the apex of the shadow of Giants Head precisely at three o'clock yesterday, one hundred feet due north, or as near north as possible. The hole shows the end of the hundred-foot line. Now, we know that Captain Harding was imprisoned on June 3, 1776; we know he buried the treasure before that date; we have a right to assume that it was only shortly before. On June 3 of any year the apex of the shadow will be in a totally different place from September 17, because of the movement of the earth about the sun and the relative changes in the sun's position. What we must do now is to find precisely where the shadow falls at three o'clock today, then make our calculations to show where it will fall say one week before June 3. Do you follow me? In other words, a difference of half a foot in the location of the apex of the shadow will make a difference of many feet at the end of one hundred feet when we follow the cipher."
At precisely three o'clock The Thinking Machine noted the position of the shadow, and then began a calculation which covered two sheets of blank paper which Hatch had in his pocket.
"This is correct," said The Thinking Machine at last as he arose and planted another stake in the ground. "There is a chance of course that we miss fire the first time because of possible seismic disturbances at sometime past or of a change in the surface of the ground; but this is mathematically correct."
Then, with the assistance of the newspaper man and the young woman, he drew his hundred-foot line, and planted a third stake.
"Dig here!" he told the workmen.