Rowan started the first transmutation that evening, cutting a pound of lead sheeting into strips and loading them into the largest crucible.
The athanor was already at six hundred degrees, the calcination threshold. The runes on the casing pulsed once as they registered the load and adjusted. Nicholas's notes said six hours at steady heat. The athanor would hold the temperature without intervention.
While the calcination ran, filling the workshop with a dry, mineral heat, they started on the press.
They worked the way they'd always worked, falling into the rhythm they'd established in the Room of Requirement without needing to discuss it. Rowan handled the runic inscription. Lawrence handled the physical construction and the mechanical design. Where the two overlapped, they argued, tested, argued again, and eventually arrived at solutions that were better than either of them would have reached alone.
Lawrence shaped the arm from tempered steel, cutting and bending with a combination of charms and hand tools. Rowan inscribed the Isa dampening array on the underside of a granite flagstone from the yard, four runes at the cardinal points connected by scored channels. When he activated them, the stone became perfectly inert. Lawrence pressed his palm to the surface and held it there for several seconds, feeling for any trace of resonance from the building settling around them. There was none.
The Raido runes along the arm came next, three of them spaced to create a repeating motion pattern that would guide the arm through the same arc every time. Lawrence inscribed a secondary Raido on the pivot joint, barely three millimetres across, working under his jeweller's loupe with an intense focus that made him go silent for hours.
The carving tip was the next day's problem. They needed a diamond-tipped scribe from a Muggle jeweller's workshop, and the Sowilo inscription on the shaft required precision work that Lawrence wanted to do fresh.
Rowan made the trip to Muggle London the following afternoon. A shop east of Charing Cross Road stocked precision engraving tools, and the craftsman behind the counter sold him a diamond-tipped scribe for four shillings without asking what a boy his age needed it for.
Lawrence had the press body assembled and waiting when he returned. The granite base with its dampening array, the steel arm on its pivot, the Raido runes inscribed along its length. He took the scribe, examined it under his loupe, and began the Sowilo inscription on the shaft.
His first attempt was fractionally off. He caught it himself before activating, ground the lines flat with an abrasive charm, and started again with a straight-edge guide. The second was clean. They mounted the scribe, charged the Jera-Ingwaz power core, and ran the first test on a copper scrap.
The arm moved. The diamond tip bit into the copper with a quiet, controlled scraping, the Isa dampening eating any vibration before it could reach the point of contact. The Sowilo rune on the shaft pulsed as it injected energy into the fresh-cut lines. Forty seconds. A single Kenaz rune, every stroke exactly the same depth, the geometry precise in a way that no human hand could match.
They ran three more tests, refining the height settings and starting positions each time. By the third, Lawrence had the full sequence memorised. Position the disk, align the arm, charge the core, activate. Five minutes for a complete luminaire array, down from forty by hand, and the quality was better than anything either of them could achieve with their finest tools.
"We actually built the thing," Lawrence said, and there was something in his voice that went deeper than professional satisfaction. Two years of studying artificing, reading the Flamels' book, designing on paper, and the machine on the workbench was inscribing runes with more precision than a master craftsman.
The first transmutation batch completed on the morning of the fifth day, and Rowan woke before dawn to check it.
Rowan had managed each stage with the attention Nicholas's notes demanded. The calcination, six hours of lead oxidising into black powder. The dissolution, acid eating away at the oxide until the solution turned dark and then slowly cleared. The three days of fermentation, the most delicate stage, the solution sitting in the alembic at precisely controlled temperature while the essential nature of the metal shifted through the planetary hierarchy.
Saturn yielding to Jupiter, Jupiter to Mars, each transition marked by a subtle change in colour and viscosity that Rowan had learned to read during his summers with the Flamels. The notebook's marginal notes were lifelines. Step four is where most students lose concentration. Don't. And later: If the colour shifts to green, you've overheated. Start again.
The projection stage was last. The moonstone catalyst dissolved drop by drop in spirit of salt, added to the fermented solution while stirring with the silver rod. The colour shifted through coppery, gold-tinged, and finally a pale cold sheen that Nicholas's notes described as the colour of moonlight on still water.
Three hours at the precipitation temperature. When he opened the crucible, a bar of bright silver sat in a residue of spent acid and crystallised salts. Fourteen ounces. Enough for three luminaire disks, with a little left over.
He sectioned the bar with a Severing Charm, polished the first disk to a mirror finish, and set it on the press.
Lawrence placed the disk on the granite base and they looked at each other. They'd practised on copper a dozen times, but this was the first real piece, five days of work and several Galleons in consumed reagents sitting on a stone slab. Lawrence set the arm for the full five-rune array with the connecting channels, took a breath, and activated the press.
The arm descended. The diamond tip bit into the silver with a sound distinctly different from copper, a crystalline scraping that resonated through the granite. The silver conducted the Sowilo energy with an efficiency that made the copper tests look crude. Lawrence ran the arm at three-quarter speed, repositioning the disk three times to bring each rune under the arc.
After seven minutes, every line was uniform and every geometric relationship precise. Rowan examined the finished disk under Lawrence's loupe and found nothing to correct.
He touched his wand to the Kenaz core.
White light filled the workshop, clean and unwavering. The copper prototypes had produced an amber glow. This was something else entirely. The silver substrate conducted the array's energy so efficiently that the Jera cycling runes barely had to work. The light was simply there, as bright and colourless as the electric arc lamps on the Victoria Embankment that had given him the idea in the first place.
Clara came down the stairs, drawn by the change in the quality of light filtering up from the workshop. She stood in the doorway and looked at the disk in Rowan's hand for a long moment.
"You explained what these would do when you hired me," she said, quietly. "I believed you, but I don't think I really understood until just now what it would actually look like."
She took the disk from him and held it up beside the window. The luminaire matched the afternoon daylight almost exactly.
The production cycle was straightforward. Three to four silver disks every four to five days through the transmutation process. Seven minutes per disk on the press. Nine silver units for a proper display and initial sales stock.
The days folded into a rhythm. Mornings were transmutation, Rowan advancing each batch through its stages with the methodical patience Nicholas had drilled into him.
Afternoons were press work. Lawrence refined the process with each iteration, finding the optimal arm speed for silver, adjusting the depth settings, building a positioning jig from scrap wood and brass pins that eliminated any guesswork in aligning the disk. By the fourth silver unit, he had the full inscription down to six minutes.
Clara managed the shop floor, arranging displays and writing product descriptions on cards for the cases. Once that was done, she started learning the workshop. Rowan walked her through the transmutation stages and Lawrence taught her the press settings. Someone would need to keep production running when they went back to Hogwarts in September.
The response from Dervish and Banges arrived midweek. They could produce the glass housings to Rowan's specifications. Six sample pieces at twelve Sickles each, ready in a week. Standing rate of ten Sickles per piece for larger orders.
In the evenings, once Lawrence and Clara had gone upstairs, Rowan turned to the other problem that had been nagging at him since they'd moved in.
He'd searched Flourish and Blotts for books on ward magic the day they bought the shop and found almost nothing. The assistant had confirmed what he already suspected: ward magic was passed down privately within pureblood families. The published material assumed you already knew the basics from home.
Which meant Rowan would have to work from what he did know.