"A buried treasure?" Allouette frowned at the stump. "Wizard, have you any skill as a douser?"
The children looked up at Gregory in alarm and huddled against their mother, who clutched them tight, staring at the wizard with wide and frightened eyes.
"Stuff and nonsense!" Allouette told them. "A wizard is a blessing if he is on your side. How say you, man of magic?"
Gregory shook his head. "I could cast such a spell, but it would be quicker to calculate the lay of the shadow."
"Calculate?" Allouette turned to him, brow furrowed. "How would you do that? Pythagoras's theorem? But we know not the length of any side!"
"True." Gregory smiled at her, eyes glowing. "But as you have seen, the tree and its shadow form two legs of a triangle. If we can learn its height and the position of the sun on Midsummer's Eve, we can learn the angle of the line between the top of the tree and the top of the shadow."
"By what method?"
"The answer," Gregory said, "lies in geometry."
"Geometry? What is that?"
Gregory's eyes widened in surprise. "You know algebra but do not know geometry?"
"Have I not but now said it?" Allouette demanded. "You know for which tasks I was trained. They did not require geometry."
"I shall demonstrate it, then, if we can discover where the sun rose on Midsummer's Eve."
"I can tell you that, sir," Dame Musgrave said. "Herschel remarked upon it every year, for it reminded him of the treasure he could no longer find."
"Where, then?" Gregory asked, too mildly. Allouette glanced at him, recognizing the sign of interest. She could not blame him; the puzzle intrigued her, too.
"Yon." Dame Musgrave pointed. "Just over the northern tower of the gatehouse."
Gregory gazed at the structure, pursing his lips. "Good, good. Now for the height of the tree."
"Let us measure the thickness of the stump," Allouette suggested, "then find three other oaks of the same thickness and learn their heights."
"Figure the average?" Gregory nodded, smiling with pleasure. "That will give us a good estimate of the old oak's height. Come, let us set about it!"
Allouette soon had the average height of three forty-inch-thick oaks.
Gregory said, "We must wait until the sun is even with the top of the tower."
"Wherefore?" Allouette demanded.
"So that we may discover the length of a shadow at that hour," Gregory said.
Allouette's expression said that she did not understand. Then suddenly it cleared. "The sun will be at the same angle as it is on Midsummer's Eve, and will cast the same length of shadow!"
"That is it." Gregory nodded vigorously. "Then we have only to strike the path it would have traced on Midsummer's Eve—unless we wish to wait a week and see."
"I shall manage with the estimate, thank you."
They had not long to wait, only a quarter of an hour. When the sun was level with the top of the tower, Gregory looked down at his shadow and asked, "How long is it?"
Allouette gave him an odd look but stepped off the length of his shadow, heel to toe. "Nine feet."
"I am just six feet tall," Gregory told her. "How tall is your average oak?"
"Sixty-four feet." She smiled, eyes bright. "If a six-foot-tall man casts a shadow nine feet long, a sixty-four-foot oak would cast a shadow ninety-six feet long."
"Well calculated, and instantly!"
Gregory thrilled to know she was learning the concepts so quickly and thoroughly. He sketched out the problem so that Allouette could calculate the angle of the evening sun from her average oak height, then the location of the fallen tree's shadow. She jumped to her feet, pink with excitement. "Come, wizard! We must discover if we have calculated aright!"
Gregory rose and hurried after her, protesting, "Do not expect too much. We only knew the average height, after all. We may need to probe ten square yards to find it."
"Ten square yards instead of an acre?" Allouette called back over her shoulder. "A good bargain indeed!"
The widow followed with her children, wide-eyed and wondering.
Allouette whirled at the tree stump, setting the back of her heel against it, then paced off the distance and stopped, pointing at the ground. "There! Will you move the earth, wizard, or shall I?"
"You may have the honor of the first excavation," Gregory said with a smile. "If you tire, I shall take it up."
Allouette gave him a strange little frown as though wondering if he were mocking her, but turned to glare at the earth. It burst into a fountain of loam, dirt shooting up into the air in a tightly controlled spray that fell neatly to the north in a growing mound.
The children cried out in fear and clung to their mother, who, sadly, was in little better condition than they.
The last scatter of dirt fell on the heap, and Allouette scowled down. "Three feet. That should be enough."
"Should." Gregory looked down into a neat cylinder a foot in diameter. "Let us widen it to three feet."
She eyed him askance, wondering if that was really admiration in his voice. "It took small enough skill, you know."
"I know just the opposite. Nevertheless, stand away from the spray and let us see if I can perform in as tidy a fashion as yourself."
Allouette stepped back beside him and the earth erupted again, as though a giant mole were trying to claw his way back into his lightless home. It rose in a nearly solid column for minutes as Gregory stared at it with a knit brow, digging by telekinesis and trying to equal Allouette's skill. Abruptly he relaxed and the flow stopped. "Boy," he said to the widow's eldest, "go look in that hole and tell me what you see."
The lad glanced up at his mother for reassurance, but she took firm hold of his hand, took his sib's too, and went with him. All three of them peered down into the excavation—a very ragged circle, to Gregory's chagrin—and exclaimed with wonder.
"I see a chest, sir!" the lad cried. " 'Tis a wooden chest, banded with brass and fastened with a huge lock."
Allouette gave a shriek of joy and threw her arms around Gregory in triumph. "We have found it!"
He stood rigid for a moment, wondering what Geoffrey would have done in this situation, then clasped his arms around her waist and whirled her about, grinning. "You have calculated marvelously."
"Liar!" She pushed away from him but looked up with glowing eyes. "It is you who did the calculations, but I shall be able to when next I need. ... Ho! Leave be! It is too heavy for you!"
Turning, Gregory saw the eldest boy standing in the hole, heaving at the little chest. He grinned and stepped over to the lad. "Is it so weighty, then? That is good news. Let me help."
The boy gave a shout of fright as the box floated upward in his grip. He let go as if it were hot metal, but it kept on rising of its own accord—or Gregory's.
He let it float to the ground. "Dame Musgrave, have you the key?"
"That, at least, my husband did leave me." The widow came forward, pulling out a key and fitting it to the lock. She tried to turn it and frowned with the effort. "It moves, but scarcely."
"It has lain long in the damp with no oil," Gregory explained, then turned to Allouette. "Will you aid?"
"Why not you?" Allouette retorted. "I have never seen a telekinetic warlock before. Surely you can manage!"
"My father seems to have had a skill Gramarye telepaths lack," Gregory acknowledged, "but you seem to have it in greater measure than I—or at least have it under greater control."
"Well, then, if I must." Allouette didn't really seem to be upset at the news. She glared at the lock, saying, "Turn, good dame."
The widow's lips pressed thin with effort and the lock groaned, then gave and fell open.
"Well done," Gregory said softly.
Allouette shrugged impatiently. "A bagatelle."
"Not to them."
Dame Musgrave yanked the lock loose from the hasp, opened the chest, and gasped.