Richard went to the lectern, where his notes already rested. He was glad to grasp the side with one hand and steady himself; this was no time to look shaky, insidious malady or no. He straightened, faced the audience with level gaze, took a full breath, and began.
“Thank you, Dr. Comber. Thank you all for coming. As you’ve heard, this will be a demonstration of the Earth’s rotation, by means of mathematics and modern physics used together. Since many of you are able to stay only for the hour allotted to the lecture, we’ll start the physical demonstration first and let it run. I will explain the reasoning while you observe what occurs.” Richard turned slightly and gestured toward the pendulum. “You see before you a weight, suspended by a cord from as high up as the hall allows. As you can see, it’s free to swing in any direction. Notice the sewing needle attached to the bottom of the iron ball with sealing wax, the degree circle marked on the large sheet of paper lying directly beneath the point of suspension, and the narrow ring of sand on the paper. Each time the needle crosses the ring, it will sweep aside a few grains of sand to mark the place where it crossed. The whole apparatus together is called the Foucault pendulum.
“As you can see, we have a clock already running. This is a very accurate laboratory instrument, made in Grantville. Scholar Crosfield will start the pendulum for us now.”
Thomas Crosfield was awake enough today, and blessed with steady hands as well. He stepped forward shielding a lighted candle behind his hand, and gingerly knelt by the pendulum, taking care not to breathe upon it.
Richard fastened his eye on the clock as it came up to the minute. He called out, “Five. Four. Three. Two. One. Loose.”
On that word, Tom brought up the candle and burned through the thread holding back the pendulum. The ball swung away in a stately arc toward the sand ring, while Tom stepped back and blew out the candle. There was the faintest of sounds as the needle flicked through the sand. He returned to his seat and took up a lead pencil and paper.
“Scholar Crosfield has written down the time the pendulum started, and the angle where it first crossed the degree circle. He will continue to do this periodically. By this we will be able to measure the rate at which the plane of oscillation rotates.
“As the pendulum moves, it’s acted upon by the forces imparted by the motion and gravity of the Earth. Starting with the Newtonian equations for these forces and the resulting acceleration of the moving ball, we can show by mathematical proof that at the latitude of Cambridge the plane in which the ball swings must rotate by two hundred and eighty-four degrees per day relative to the stars, or two hundred and eighty-five relative to the sun, just under twelve degrees per hour.” He turned to the movable blackboard standing near the lectern, already filled with the first part of the accompanying derivation. “We begin with the equation for the force of gravity…”
Today Richard had no lectures to give or attend. John Rant had arranged to call later on, to ask his advice regarding the best way to present a seminar on proof by infinite series. For now, though, it was a perfect time to immerse himself in correcting the latest sheaf of typeset proofs for the English edition of the probability textbook. It wasn’t a large batch today; there should be plenty of time to make progress on the translation work as well. In truth, he was happy to be able to spend most of the day seated. Well, perhaps he’d feel more like visiting one of the taverns tomorrow, or just walking by the river. He glanced out the window at a few students hurrying past the great fountain in the court below-it was just as well to be inside in any case. He took up his pen and set to working steadily through the stack by the watery light from the late autumn sky.
Shortly before the midday meal Richard finished the proofreading and set it aside. He was the picture of an absentminded professor as he hurried across the court toward the dining hall, in spite of being far below that exalted rank. He didn’t seek company at dinner today, being occupied in considering the practicality of constructing the apparatus for the measurement of the universal gravitation constant-without sending to the piano makers in Grantville for a length of fine-gauge music wire. Could it be done with a common lute string? Perhaps some testing might reveal the answer.
He returned still deep in thought to his room, and settled in to rendering probability theory clearly and concisely in Latin, a satisfying challenge. The tingling in two fingers of his right hand faded from his notice. He wrote in the spare up-time style, with no classical allusions, metaphors, or digressions beyond the bounds of mathematics itself. Richard wrote, crossed out, wrote again, made editing marks, wrote again. After a time the weather became typically English. Rain, sun, overcast, wind, at twenty-minute intervals. The sky abruptly turned fair with an unseasonably warm breeze, and Richard thought to air out his room while he had the chance. He opened the windows and the door to the staircase.
He went back to his translation. Hmm, what would be the best way to express the concept of expectation?
There was a soft caress against his ankle. He looked down at orange fur and blue eyes. Nan was looking up at him. He reached down to stroke her side. She leaped to his lap, and from there to the table. She sniffed at the inkwell and brushed her upraised tail against his nose. Richard lifted her aside, off his rough draft, and began scratching her behind the ears to tempt her to stay where she was. She settled down with one paw draped limply over the edge, purring and swishing her tail from side to side. Richard was a little too distracted at the moment to remember whose cat she was, but it hardly seemed to matter to her anyway. His hand continued moving, back and forth, as his mind returned to pondering the problem. Perhaps… He weighed alternative constructions, as they took shape in his mind. After a time footsteps sounded on the staircase. Richard listened with half an ear for a moment, but he didn’t recognize the step, and it was early for John. He wrote another sentence.
There was a knock on the door frame. Richard looked up. “Oh, Dr. Comber.” He started to rise.
Dr. Comber waved him back down. “Do you have a few moments, Richard? I have some questions.”
“Certainly.” Richard waved his hand toward the second chair.
As Dr. Comber drew it up to the other side of the writing table and settled down, Nan opened her eyes. He reached out his hand and she leaned into it, while he gathered his words. His gaze swept across the stacked page proofs and the scattered manuscript sheets on the table. “How does it go, then?” Nan rose to her feet at the broken silence, jumped off the table, and sauntered off to parts unknown.
“Very well. There should be only one more batch of page proofs after these, before the English edition can go to press and I can think of offering a course of lectures. There are already inquiries for copies. As to the Latin manuscript, it’s nearing the halfway mark. The Latin lexicographers helped me greatly in devising suitable terms for the new principles before I left Grantville, and they’ve added them to their technical dictionary.”
“Excellent. But I was asking after your health, more than the work.”
“Not too bad.” He reached for the cane leaning against the bookcase and held it up. “I have this, but seldom need it. The special candle lamp with the focusing lens and mirror that I brought for the microprint viewer helps me work after dark.”
“You didn’t need that cane at all, earlier. Perhaps we’d better find you quarters downstairs for next term. I’ll say a word to the bursar and see what might be done. More difficulties seeing, too? You have my sympathy. I’m thankful to have spectacles, these days. But you’re able to continue teaching? I know how greatly you wish it.”
“Yes, and it gives me greater satisfaction to aid others in taking up the work. I could never bring such a body of new knowledge to Cambridge by myself. No man could, alone.”
“Indeed. And so we come to my reason for calling on you today.”
John Rant appeared in the doorway. “Oh, Dr. Comber, I didn’t know you were with Richard. Should I come back later?”
“No, stay, you might have some thoughts to illuminate the discussion, with all the time you’ve spent together in study and inquiry.”
Both chairs being occupied, John leaned against the wall beside the door and folded his arms, an expectant expression on his face.
“Richard, I’ve been much occupied with many matters, but you’ve spoken before of what new learning this university might offer to our students. I would like a more thorough understanding of what it consists, and how large a body of knowledge it might be.”
“You’re giving consideration to this, then?”
“It’s far too soon to say that. Before I can consider anything, or usefully speak of such things with the fellows and officers, I must understand the meaning of these subjects you say are studied now in the Germanies, and as well the numbers of those to do the instructing. Particularly the latter. Do you know, this university has been trying
