We ended up back in Deftshire, holed up once again in the inn. News travels fast, but not as fast as Windboy and I. Maybe we'd get lucky, and the story of the man with the glider and the "flying demon boy" would die out before it left London. But if not, we might be living on borrowed time in this town, too.
And that wasn't the only borrowed time we were living on. The time-warp hurricane's 17-day countdown was now on day 5.
"Unfortunately," I told him, "Copper wire is only the first step. It'll work to carry the electric current, and it'll work for the antenna, but to extract any information about the presence or absence of radio waves, we're going to need other circuit components." I took a deep breath. "Starting with a rectifier. Um . . . you remember when I said we didn't need a diode?"
"No," Windboy said. "I remember you talked about building a radio circuit, when we first came to this inn, but all the details just bewildered me."
"Mmmm," I nodded. "I guess I do kind of ramble, don't I. Well, anyway, I was wrong. A piezoelectric earphone is the only component I can think of that can turn a super-weak electrical signal into something we can see or hear, and which we might have a snowball's chance in hell of actually building. But an 11.42 megahertz oscillation is going to be way too fast for any piezo crystal to keep up with, let alone the diaphragm it's attached to. The noise in that 11.42 MHz band, though — it's not true Amplitude Modulation, but it'll still make the amplitude go up-and-down at a much slower rate than the carrier wave. I remember listening in to a time-warp tornado's radio noise once, over a modern 1967 receiver with vacuum tubes and everything. I could hear a definite hiss, like white noise, punctuated by pings and pops like static. The noise came and went every few seconds. And to hear that, in a crystal earpiece, we're going to need a diode."
Windboy shrugged. "So how do we make a diode?"
"Well," I rubbed my chin, "The traditional crystal radios in the early 20th century used a lead sulfide crystal and a super-thin 'cat whisker' contact wire. But I remember hearing about ways to improvise a diode from household items. Soldiers in World War 2 would sometimes make diodes out of rusty razor blades and pieces of pencil lead — pencils didn't really use lead in that era, of course, they were made out of graphite. You could also use copper oxide instead of iron oxide, by baking a piece of copper in the oven until it turned dark brown." I sighed. "Rusty iron would probably be a lot easier to come by in 1127, but oxidized copper makes for a much better semiconductor."
Windboy nodded. "So what about graphite?"
I frowned. "It's just carbon, but the atoms have to be in a precise lattice. We didn't figure out how to make it artificially until the 19th century. It occurs naturally in some mineral formations, but you have to know where to mine for it. I remember hearing something about a giant graphite deposit being discovered in England some time in the 16th century, but that was just something a prof mentioned in a class years ago. It wasn't even on the test. Without a copy of a 1967 encyclopedia, I'd never be able to pinpoint it.
"But there's another option, if we can get a piece of wire small enough and a mount to hold it in. It's called a cat's whisker. If the contact point is small enough, even regular copper can act as one side of a P-N junction." I stood up. "Come on, let's see if there's a coppersmith in any neighboring towns. Turning a copper wire into a copper needle can't be that tough to do."
We walked out to the secluded meadow again, with my (folded) hang glider in tow just as before, then took to the skies. We flew northwest this time; the farther from London we could get, the better the chances of the towns not having heard about us yet. Finally, we noticed a settlement larger than Deftshire (though still much, much smaller than London). We landed the usual mile away and walked into town.
Windboy couldn't resist talking up the locals. It didn't take long to find out that this town did have a coopersmith, though most of his time was spent binding wooden barrels together with copper hoops. We walked to his shop — a two-story affair with what was presumably the coopersmith's home on the top floor — and rang the little copper bell outside his door.
The door opened and a rather pleasant-looking woman in housemaid clothing presented herself. "Hello, strangers! You in need of some barrels?"
"Actually," I said, "We're in need of a coppersmith."
She raised her eyebrows. "Really." She turned to face the back of the shop, and yelled, "John! Customers!"
The woman vanished into the house, and a tall, wide man in a shop apron replaced her. "So what brings you to John's copperworks?"
I showed him the spool of "thin" copper wire I'd brought with me. "This is the thinnest wire I could buy elsewhere. I need something a lot thinner. I need a small length of super-thin copper wire, maybe an inch or two long, that basically ends in a needle-sharp point."
I hoped they had inches back in 1127.
"Hm," John squinted at the wire in my hand. "I should be able to do that. It's nice to have a challenge for a change. If I do it with a bit of your wire, it'll cost you a ha'penny."
"Sounds reasonable," I said. "I'm also going to need . . . um, do you have a forge?"
"I wouldn't be much of a cooper if I didn't have a forge," he said. He pointed to a stone cube in the back of his shop, which had a smokestack leading out the side of the building. The air right in front of it rippled with heat.
"Good," I said. "I'm also going to need you to take a flat piece of copper about an inch on a side or smaller, polish it to a shine, and then bake it in your forge for about a half an hour."
He shook his head. "That would defeat the purpose of polishing it. You get copper that hot without melting it, and it gets a dark brown coating on its surface."
I nodded. "I'm counting on that."
This was a new one for John the coppersmith. "Uh, okay. I'll do that for tuppence, my materials included."
"All right, then," I said. I took out a pair of clippers I'd had Windboy buy for me back in Deftshire, and cut off a couple of inches of copper wire. I handed him this length, saying "For the ultra-thin wire. Oh — and could you coil it a little bit, to make it springy?"
"Excellent," I said, then plucked two-and-a-half pence out of my coin pouch and handed them over as well, saying "And for your trouble."
"Payment in advance?" John said. "I like that. I've got a couple of barrels I need to finish first, but if you come back in three hours I should have both items ready for you."
"Thanks!" I said. "See you this afternoon."
While John worked his copper magic, I went with Windboy to get some small blocks of wood and some carving tools. A cat's whisker junction demanded a mounting station to hold it steady. Fortunately, I still had the woodworking tools from when I was building the hang glider, but this would demand finer precision. I'd also made sure to take the burlap sack along, which I'd bought from Tim the coopersmith back in London, so as not to be fumbling with all the little items I'd be buying.
Windboy also took the opportunity to be his friendly self with the locals, and to partake of some of the local chow. I couldn't blame him, the gruel they'd been serving us at the inn in Deftshire was hardly satisfying. We shared an entire leg of roast boar, and this place served us mead instead of plain old ale. But it wasn't cheap; tuppence just for one meal for the both of us. My coin pouch was getting disturbingly light.
We still had some time to kill before the coppersmith would be done. I said to Windboy, "For the earpiece, I'm going to need a piezoelectric crystal and a thin metal diaphragm. I can ask John to make us one of the latter. Plain old quartz will work for the piezo crystal, but getting a thin chip of it is going to be tricky. No idea how I'm going to attach the wires to the crystal without solder."
"Let's ask around then," Windboy replied, "And see if anybody has some quartz."
As it turned out, at an open-air market on the far side of town, one vendor was showing off crystals for sale. There were no real gemstones among them, of course; each was a chunk of some common, pretty rock. If this had been 1967, I would have guessed they were for hippies to focus their "psychic powers." I wasn't sure if she was selling them as decorations, or as talismans to ward off evil spirits. But there were about a dozen chunks of semi-clear quartz among them, and that was what mattered.
"How much for the quartz?" I asked her, pointing.
She seemed surprised I was interested in quartz. Perhaps they weren't pretty enough to garner much attention. "I'll let you have two pieces for a farthing."
I counted them. "I don't know how much I'm going to need, so I'll take all twelve." I handed her three pence.
"Hmm!" she said, examining the coins to make sure they were genuine. "Thank you, sir! They're all yours."
I scooped them into my burlap sack, and we went on our way back toward the coppersmith's shop. "So," Windboy asked as we walked, "How are you going to turn those chunks of quartz into the thin chip you need?"
I shrugged. "I guess I'll just keep breaking off pieces, until one of them happens to be a thin flake."
John met us at his shop door when we arrived, and handed over both the whisker-thin wire and the oxide-coated copper square. The patina on the flat piece was exactly what I was looking for. The wire was so delicate I was worried it might get damaged jingling around in my sack with all the wood and quartz, so I put it in a pocket instead.
"By the way," I said, "I also need a very thin metal piece, a little smaller than this browned copper plate and round. This one doesn't need to be treated in a forge."
John shrugged. "I've got a piece I snipped off the end of your brown square before I put it in the forge. Lemme go pound it flat." He disappeared back into the shop before we could object, and after some hammering noises he came back with an irregularly shaped, thin disc of copper a little less than an inch across. "Will this do?"
I turned the piece edge-on in my hand. It was almost invisibly thin. "Perfect," I said.
"I'll let you have it for a farthing," John declared.
I handed him a piece from one of the coins that had been cut into four slices. He seemed satisfied by this.
"Pleasure doin' business with you." John waved one hand, then went back inside and shut his door.
"Let's get these back to our workshop," I said to Windboy.
Once more, we walked far enough out of town so as not to be seen. Once more, we found a field and took off. And once more, we landed in the meadow outside Deftshire and walked back in. The process reminded me of going to the airport in Los Angeles and flying on a plane to Seattle, except without the crowds.
Back in our room at the inn — which was still draining two pence from my ever-lightening coin pouch every night — I started to work on the wooden holder for the diode assembly. "This is going to take a while," I told Windboy. "You could go back into town and talk to your new friends there."
"Actually," Windboy said, "I think I'd better watch you build this."
"Uh," I said. "I usually feel a bit uncomfortable with someone watching me work over my shoulder. It's like being judged. Why do you want to watch?"
Windboy took a slow breath. "If — no, when we find the time-warp hurricane, and I can get to its eye for the next reset, I'll be going back to my usual life. I'll be popping out of other time-warp hurricanes, visiting different eras, and coming back again. This trip to 1127 was the first time I've lost track of a hurricane after leaving it, but I can't be sure it'll be the last." He looked me in the eye. "If I find myself in a similar situation again, someone like you might not be around. I'm going to need to know how to build a detector on my own."
Oh. Oh my. I hadn't considered that. This poor, cursed kid . . . He didn't just need to watch me. He needed a teacher.
"All right," I said. "Let me show you the principle, so you can see what I'm trying to accomplish." I held up the tarnished copper plate between two fingers. "The brown coating on the copper is our semi-conductor. It's actually a thin layer of copper oxide. It'll conduct electricity under some circumstances, but not others." I picked up the ultra-thin springy wire. "When the tip of this wire makes contact with the tarnished surface just right," I gently touched the pin-tip of the spring-wire to the top of the browned copper, "It forms a diode junction. Electric current will conduct through it in one direction, but not the other. But it's really picky, and you can't tell ahead of time exactly where on the copper-oxide surface you need to touch it. So, I need to build a small wooden rig that will hold the semiconductor plate steady, and let me move the thin wire around so that it can touch any point on the semiconductor I choose. And, it has to hold the wire in place when I'm not moving it . . ."
It took the rest of the day, and a bit of the next morning, to build a rig that worked. I stopped and explained every carving shave I made, every nail I pounded in, ever bit of glue I laid down. I also figured we might as well make two of these; that way, Windboy could work on one of his own and get a feel for building it with his own hands. I finally got my rig to hold the wire in place in any position I wanted, and then we tried doing the same in Windboy's rig. It took a few added touches, but we got it to work too. The look on Windboy's face was worth all the effort. I felt confident that he could build one of these on his own, if he had to.
"And there we go," I said. "The crystal, in our crystal radio." I chuckled. "And it doesn't even have a crystal in it!"
Unfortunately, I had no way of testing it. There weren't exactly a lot of A.C. sources and ammeters sitting around in 1127 A.D.. The best I could hope for was to build the earpiece, wire it up to the diode, put out a long antenna, and hope against hope that all the components worked. And we were already on day 6 of the time-warp hurricane's 17-day duration.
"For the earpiece," I explained to Windboy, holding up the thin disc the coppersmith had made for us at the end yesterday, "This is going to be our diaphragm. If we can make it vibrate back-and-forth, it'll make noise. It'll be really faint, so we'll need to send the sound through a funnel into one of our ears to be able to hear anything. I didn't really think about that part yet. But first thing's first. To get it to vibrate, we're going to need to attach it to that thin flake of quartz I've been talking about." I picked up a hammer and one of the 12 quartz lumps. "Let's see if we can make one."
I put the quartz on a stone floor tile, and brought the hammer down on it, hard. It shattered like glass. Most of the fragments were smaller quartz lumps, utterly useless. There were a few thin shards, but they were all too short or narrow or bulgy in the middle to work as a piezoelectric flake. Damn. "Well, that didn't work," I said to Windboy. "Maybe I need to chip away at it more slowly." I put another big piece of quartz on the floor tile, and tapped it on one edge with the hammer until a piece broke off. It was still the wrong size and shape, but it was closer.
"Can I try?" Windboy asked.
"Sure," I said. I handed him the hammer and stood back from the floor tile. Windboy knelt in front of it, holding the crystal between two fingers, and gently, deftly tapped. Another slice came off, far too thick to be useful. Then he closed his eyes, made a pinching gesture, and blew out his breath across a range of pitches. He was talking to the wind again. A soft breeze whispered back to him in his ear. He tilted the hammer at a slight angle, and tapped on the quartz crystal again.
A single flake sheared off. It was as thin as a human hair. He picked it up between two fingers and showed me. "Will this do?"
My eyes opened wide. "Yeah!" I held out my hand, and he dropped the flake onto my palm. The closer I looked at it, the more perfect it seemed. "I think we have our piezoelectric crystal." I looked back at Windboy. "You've got a really handy companion there."
I got to work immediately, first gluing the quartz flake onto the diaphragm and then attaching lengths of wire to either end of the quartz. The wire attachments were the trickiest part. Not only was solder not a thing in the 12th century, neither was electrical tape. The best I could hope for was to flatten out the end of each wire, press both wires to either end of the quartz surface, apply a bunch of glue on top of each contact point, and then put a strip of very thin leather across both of them before the glue dried. Or maybe it was a strip of very thin deerskin, I couldn't tell animal hides apart. As with all the other gluing jobs we'd had to do, we needed to let it dry overnight.
While the glue was setting, I talked with Windboy over ideas for a housing. We needed a little chamber that would allow the diaphragm to rest safely inside, with something protruding from one end with a hole in the center so that we could plug it into our ears. I'd seen plenty of earpieces made out of molded plastic, but plastic wouldn't be invented until the mid-19th century. I could, conceivably, try to make the housing out of wood, but the wooden rig for the diode had taxed my woodworking skills to their limit. The earpiece would need to be even smaller and more precisely shaped. Bone, perhaps? I didn't know the first thing about bone carving; and we'd need to make two separate pieces, put the diaphragm between them, and then glue them together. I wasn't even sure the glue we were using could work on bone.
Well . . . maybe we'd get lucky, and the sound would be strong enough that we could hear it just by holding the bare diaphragm assembly up to our ears. We could afford not to get it right the first day.
I spent the rest of the evening getting a feel for how much I could bend the "thin" wire back-and-forth before metal fatigue set in. With no insulation around the wires, I'd need to put pieces of something non-conductive between any pairs of wires that touched where they shouldn't. I'd also need to twist together the wires that should be touching tightly. Without any tuning elements, the circuit was extremely simple — but it still needed an antenna. A long one. I might need Windboy's help in making the antenna wire stand up vertically. We'd need as tall an aerial as we could get.
On the next day — day 7 — it was time to try my makeshift radio detector out.