“It’s bigger than ours,” came a gloomy voice. Some friendly memory helped Shef to recognize it.
“Anything’s bigger than yours, Odda,” he replied. “What are you waiting for, Osmod? Pull the bolt.”
As he saw Osmod turn, with a certain fear, to the bolt, Shef himself turned his back, ran up the stone steps to the parapet of the left-hand tower. Behind him he heard a squeak of protesting metal being drawn. Then a long scraping noise which ended in a great crash. He looked round just in time to see the sling release and the boulder that two mighty men had strained to lift fly into the sky like a pebble.
As it soared out on its long arc Shef followed it, ignoring the groans of protesting timber, the shouts and yells from the crew. The top of its arc, there, must be the midway point. He was sure it was on line for “War-Wolf.” But the range?
Shef let the breath escape in a long sigh. He knew already it was going to be over, even well over. His shot had been far worse than the enemy’s. The thump and cloud of dust had come down well over. How well over? He put down the far-seer with its cloudy lenses, strained his one eye to get a sure view. There were too many things in the way. At a guess he would say forty yards over. Consider. How many men, stretched head to foot, between what he could see of “War-Wolf” and the already settling dust-cloud. Shef counted, nodding his head unconsciously to each imaginary six feet. Maybe not forty yards. More like thirty-five. Under rather than over. Say thirty-four.
Now how far was it from “War-Wolf” to the gate? The guard captain Malachi was standing by him, saying nothing but looking anxious.
“Think carefully. You must have walked that road many times. How far is it from the gate to their machine? Think of it in double paces.”
A long pause. “I would say one hundred and forty.” And twenty, already paced out, from the center-line of his own machine to this side of the gate. A hundred and sixty, times five and a half feet, was the range he meant to shoot. That sum, plus thirty-four, times three, was what he had shot. He had to reduce the fifteen-hundred-pound throw weight in proportion to the reduced distance to get a hit with a boulder of the same weight. Two days ago he would have thrown his hands up, declared the sum impossible. Now…
Shef sprinted down the steps again to where his sand table waited. Osmod met him with a face of woe. “The machine. It’s falling apart. The weight’s too big for it. Needs side-braces, like what they’ve got…”
Shef pushed him aside. “Wedge everything back as best you can, use nails if you have to. It has to hold together for one more shot. Tell the men to unload, winch up, put in ten hundred pounds. Then wait.”
He bent to his table, lines already drawn for the first of his sums. One hundred and sixty, times five, add on eighty—that was easy. Write “880” in the sand. Thirty-four, times three, add it on, write “982” in the sand.
Now, divide fifteen into 982 to find out how much distance to each hundred-pound bag. And then, divide that figure into the 880. Shef struggled on, absorbed. His own men watched him curiously. Solomon and Malachi exchanged glances. Either of them, they suspected, could have carried out the operation faster, as could any trader in the market. But then a market-trader would not have known what it was that the king of the barbarians was trying to do. He might be near-illiterate. But he had made the machine. The flares, the kites, the crossbows. Best to trust to what the Arabs would call his iqbal. The odor of success.
Shef straightened. He could not do quantities less than one, had had to double his numbers both sides to get a fair approximation, but he knew the answer.
“Ten hundred-pound bags in? Right, add three more. Open a fourth. Take half out. Exactly half.”
Shef bent over the open bag. There should be fifty pounds in it. According to his figures he should now take out seven more. What difference could that possibly make to a boulder of the size they were throwing? Grimly he scrabbled out what seemed to him to be seven pounds of dirt, the same weight as two days’ rations. He twisted the bag closed, stepped up the ladder, hurled it in on top of the pile.