Chapter 26 #2
“Siderography,” he said softly. “I have just learned that the name of this process is siderography.”
“Ah, yes—that’s the term Wrexford used!” she responded.
“But I’m afraid he hasn’t an artistic bone in his body, and I thought that I might be able to offer some technical explanation to him if I could glean a rudimentary understanding on why mechanical lathes can create designs that can’t be copied by hand. ”
A pause. “And as you were so eloquent about their capabilities last night …”
Manchester blew out his breath. “Well, I do know a lot about rose engines. And if it would help His Lordship—”
He looked around as the door’s bells sounded again and two elderly gentlemen entered the shop. Lowering his voice, he quickly added, “I assume you would prefer that we discuss the matter in the privacy of my office.”
At her confirming nod, he called for his golden-haired assistant to attend to the newcomers, and after apologizing to them—it turned out they were frequent customers—he escorted Charlotte through one of the side archways and down a short corridor to a large and sunlit room at the back of the building, which looked out over a private rear garden.
An imposing oak and burled walnut desk, whose elegant lines and subtle carvings gave it a look of lightness despite its bulk, sat in front of a bank of diamond-paned windows. Manchester moved one of the chairs to his side of the desk and then gestured for her to join him.
Once they were settled, he opened the large leather portfolio case on his blotter and spread out a sheaf of intricate engravings.
“As it happens I was planning on reviewing a number of historical designs to see if I could pick out some specific patterns that might be well suited for use on banknotes.”
Intrigued, Charlotte leaned forward to study the top sheets. “Forgive me if this is a foolish question, but why do you believe that a mechanical device can create patterns that can’t be copied by hand?”
“Actually, that’s an incredibly insightful question and gets to the heart of the matter.” He pulled out a sketchbook from his desk drawer and took up a pencil. “It’s fairly easy to draw curves and curlicues, and even straight lines by hand, but perfect circles are far harder.”
“But we can do so with precision instruments, like a surveyor’s compass,” observed Charlotte.
He smiled. “Yes. But now we come to one of the key points. A rose engine is specifically designed to create small, detailed patterns like those used for banknotes,” he clarified.
“They are run by a system of gears and ratcheting levers. Because of that, we can adjust the machine to create overlapping circles with precisely the same space between them—something that is virtually impossible to do using just the human eye. We can also manipulate the angles of our mechanical cutting blades to make overlapping patterns that are dreadfully difficult for a person to copy by hand, like overlapping circles and ovals that make elegant figure-eight variations.”
He drew out an example from among the piles of paper and handed it to her, along with a magnifying glass.
A gasp of surprise slipped from her lips as she looked closely at the sheet, which was far more intricate than the samples she had seen at Ibbetson’s demonstration. Her amazement grew as she enlarged the image with the glass lens. “These are dizzyingly complex,” she said.
“Indeed they are.” Manchester gave a mirthless chuckle. “Perhaps too complex.”
“Aim higher,” counseled Wrexford after both Raven and Eddy had missed their first round of shots at the small glass bottles he had set up as targets on a nearby stone wall.
“Wind, humidity, temperature—all these factors come into play when one leaves the controlled confines of an indoor shooting gallery. So you must adjust accordingly.”
The breeze suddenly freshened, stirring whooshing whispers through the tall meadow grasses of the deserted section of Hounslow Heath that the earl had chosen for their lesson.
Eddy huffed in frustration as she watched the leaves shiver on the swaying branches. “But as the weather is constantly changing, how the devil does one ever know how to compensate?”
“Experience,” answered the earl, his mouth quirking in amusement. “Like most things one wants to do well, it takes practice, practice, and more practice. You simply learn to judge by feeling, not thinking.”
“That sounds like I’ll be an old lady before I ever manage to hit the dratted target.”
“Not necessarily.” Raven, who had immediately pulled a small book from his pocket after his two misses, looked up from the pages.
“Wrex, I actually disagree with you about not thinking. Shooting is not simply a matter of intuition. Ballistics can be understood through mathematics. Napoleon began his military career as an artillery officer, and one of the reasons he became so good at his profession was because he understood what a practical advantage mathematics gave him in achieving accuracy.”
“As the damnable jackanapes proved at the Battle of Toulon, where his gunners drove our navy from a very important base in the Mediterranean,” said Wrexford dryly.
“Until then, he had been a mere nobody, but the impressive victory brought Napoleon to the attention of France’s revolutionary government and put him on the path to his place in history. ”
“But how does mathematics help in understanding ballistics?” pressed Eddy.
After turning several pages, Raven held up a table of numbers. “One can calculate the effect of wind and distance on a moving object—also factoring in the natural force of gravity— and make adjustments in one’s aim to compensate for those factors.”
“That is true, lad. But for those of us who aren’t capable of adding, subtracting, or multiplying with the ease and speed you possess, we must simply learn by the misses we make. For example, experience can teach us to judge the wind by its feel on our cheeks.”
Eddy craned her neck to study the printed table and made a face. “How can that possibly work?”
Raven held up his finger for a moment. “The wind is blowing about five miles per hour and is angling at around forty-five degrees to our line of fire.” He did some quick mental arithmetic as he reloaded his weapon and then stepped up to the mark set by Wrexford and took aim.
BANG!
The bottle teetered and fell off the stones, the top part of its neck shattering in a spray of broken glass.
Eddy stared at him in awe. And then her face scrunched into a grimace. “I suppose I will have to ask Mr. Lynsley for extra tutoring in mathematics, though all those numbers and complicated symbols make my head spin.”
“Or I can teach you some very basic principles of ballistics that will help,” offered Raven. “It’s not necessary to calculate every variation for every shot. As Wrex says, you can learn to judge general conditions …”
The next hour passed with much thunder and grumbling, but by the end of the session, both Raven and Eddy were hitting their targets with gleeful consistency.
“Thank you,” she murmured as the two of them followed the earl back to the cart path where the carriage was waiting. “You’re really clever to understand how numbers work in so many interesting ways.”
He shrugged. “You have a gift for understanding living creatures, while I seem to have the ability to understand how a bunch of silly symbols help us solve practical problems.”
“I don’t think working with numbers will ever come naturally to me,” admitted Eddy. “But it was very nice of you to help me grasp some general principles.”
“Don’t be so hasty in deciding,” he suggested. “You never know—mathematics might grow on you once you get a little more comfortable with numbers and see them as your friends rather than the enemy.”
“W-What do you mean ‘too complex’?” demanded Charlotte, now feeling thoroughly perplexed. “Surely the more complex the design, the better?” she reasoned.
He shook his head, allowing a rueful smile. “Theoretically, you’re absolutely right. No hand-engraved copy can come close to matching the absolute precision of the original rose engine creation.”
His chair creaked as Manchester tilted back and looked up for a moment at the plaster rosettes on the painted ceiling.
“The trouble is, most people aren’t very discerning and can’t see the difference, especially on something as small as a banknote.
” He released a frustrated sigh. “So, for the moment, our mechanical expertise is all for naught.”
Charlotte frowned. “Wait! Are you now saying that it’s impossible to create banknotes that can’t be copied?”
“Not at all. Like the American Jacob Perkins, whom I mentioned last night, Applegath and his partner Cowper, along with Sir William Congreve, believe the answer lies in creating multiple guilloche designs and then combining them onto a master plate,” explained Manchester. “That is the essence of siderography.”
“Wrexford did mention that Stoneham had explained to him the basic theory of how siderography is done,” mused Charlotte.
“But he didn’t go into details, save to say it’s very complicated and involves a three-step process that converts intaglio plates to a master relief die, which then is used to recreate multiple versions of the original intaglio plate. ”