Recently, I've been looking at the history of locks - and lock picking. Fascinating subject. But, for the benefit of anyone who might find this activity suspicious, I don't plan to actually use this knowledge. My characters, however, do, and to prove it, here's an extract from 'The Hidden Libraries' (sequel to 'The Empress's Lover') which I've been working on lately.
I led the way down, with Ommet lighting lamps as he followed me. White plastered walls reflected the light and made our way clear. The steps were worn from uncounted numbers of holy feet that had passed up and down, but not to a dangerous degree, and we descended quickly until the next door came into view. At which point I stopped short.
“Ah – you did say the lower door was just like the upper one? And that the locks have never been modernised?”
“That's wrong. Come and take a look.”
Instead of ancient wood, we now faced a slab of shining metal. And instead of three strong but vulnerable old locks, it was fitted with something quite new and different.
I went down the remaining steps. Ommet followed me, with the two seamen – Mebbers and Cray – close behind.
“Well, sir, I reckon as how you've got the challenge you wanted,” Mebbers said. “I'm bu... blessed if I ever saw a door like that afore.”
“Or a lock like that,” Ommet added. “I take that is a lock, that thing with all those numbers?”
“It is a lock,” I confirmed.
Set neatly into the centre of the door were five little windows. Behind each a number showed, and next to each number was the knurled edge of a small wheel. A large handle projected from the door to one side. I tried to turn it, but predictably, it stayed firm.
“Not even a rattle,” I said, mostly to myself. “Very new. Not had time to work any looseness into it.”
“It can only have been installed in the last few months,” Ommet agreed. “Ah! I saw Brother Williface with the others, and I thought him down in the South. But he is a master smith, the best in the Order. I have no doubt that he was brought up here to install this door – and the lock. But I don't suppose he made it.”
“No. He didn't,” I confirmed. “There are very few locksmiths in the Empire who can make these, and they don't come cheap. It's called a number-lock, or sometimes a combination lock, and was invented by a genius named Deseradi Jankin. They are new, and rare – I have seen just one before, and that had just three number wheels. This must have cost the Arravines a pretty penny indeed!”
“How does it work?”
“Each set of numbers goes from zero to nine, and the correct combination of numbers must be set to release the bolt. Hence it's alternative name. With the three wheel version, that meant that there were a thousand possible different combinations. With five wheels...”
“A hundred thousand,” Ommet whispered.
“We're going to be here a while then,” said Mebbers.
“Not at all!” Ommet answered him with a brisk confidence. “Mr. Dowder is an expert! There isn't a lock in the Empire that he cannot open – and he'll deal with this one very handily, I'm sure.” He gave me an expectant look.
“Well, it may take a little while,” I said cautiously. “Obviously, we can't just try all the possible combinations, that would take far too long – but there are ways of finding the correct sequence. I'll need complete silence, though. Mebbers – if you and Cray could wait up in the vestry, please? Keep an eye open for any wandering monks.”
I waited for their footsteps to recede up the stairs, then turned my attention to the lock.
I didn't share Ommet's confidence. When I said I'd only seen one before, I meant it literally – I had seen it, at a distance, at a Locksmith's fair a year or two ago. No one was allowed to actually touch it, or even get close. There had been a lot of speculation amongst locksmiths about how the mechanism worked, and more about how it might be opened, but nobody knew for sure.
In theory, the bolt had a series of projecting lugs, whilst each number wheel turned a disk with a gap in it. When the correct number was showing, the lugs and gaps would all line up and the bolt would slide out.
It this was the case, then it should be possible to find the gap by turning the disk at the same time as applying pressure to the bolt, until the lug slipped into the gap. Only by a small amount, as the other lugs would still hold the bolt secure, but then the process could be repeated with the remaining discs until the bolt came free.
That was the theory. Now I had to see it it worked.
I turned the handle slightly and, with my ear to the door, began to turn the first wheel. Very slowly, number by number, holding my breath and listening at each turn.
My senses are very acute, and tuned to the highest pitch of concentration, I could hear the very slightest sounds. Ommet's breathing. The scuff of a shoe from Mebbers or Cray above us. A faint scurrying as of a mouse somewhere in the cracks of the stonework.
But nothing from the lock.
There was sweat dripping into my eyes. I sat back from the door, wiping my forehead with my sleeve, and suddenly aware of several aches and pains.
“How is it going?” asked Ommet.
I gave him an annoyed look. “Is the door open?”
“Apparently not. Sorry.”
“How long have I been working on it?”
“I think – perhaps an hour? You've turned that wheel through all it's numbers at least a dozen times.”
“Ah.” I turned back to the lock.
Clearly, the theory wasn't working. Either the lock mechanism was not as I had thought, or it had been machined so precisely that there was no movement at all on the bolt until all the lugs were precisely aligned.
Time to try a different approach. I adjusted my position and started again. Not with my ear to the door, this time. Not listening. Feeling. Concentrating all my attention on the movement of the knurled wheel beneath my fingers, whilst at the same time turning the handle as far as I could, putting maximum pressure on the bolt.
I didn't see the numbers. I just felt the resistance of the wheel.
And then, for a moment, I felt no resistance.
Was it real or had I imagined it? I couldn't be sure. I rolled the wheel back a fraction. There was a change. Very slight, but at one point it did move a little more freely.
I thought it did.
Number 1. The combination started with '1'.