“Sentiment is all very well,” said Wrexford. “However, it’s imperative to set emotions aside for now. We have a dangerous killer to bring to justice, as well as a financial fraud to expose.” He poured himself a cup of coffee. “That is, unless by some miracle Taviot’s consortium has actually succeeded in making its revolutionary propulsion system work.”
“Revolutionary—ha, ha, ha,” chortled Raven. He extended his forefinger and spun it round and round in a tight circle, causing Hawk and Peregrine to fall into a fit of giggling.
Cordelia stared at the boys, utterly mystified.
“Stifle your hilarity, Weasels,” said Wrexford as he opened several of the books and arranged them on his desk. To Cordelia and Sheffield he added, “Come have a look at these illustrations, and I shall explain. Once we knew what we were looking for, Tyler found some relevant information and examples in my scientific library.” He shook his head in self-disgust. “To think they were lying right under my nose.”
Heads bent low, the two of them studied the various images.
“Why, it looks to be some sort of . . .” Cordelia looked up. “Some sort of screw?”
“Yes, it is based on some of the same basic principles,” replied the earl. “But it’s called apropeller.” He made a face. “And I feel like a complete lackwit for not having thought of the possibility before now. The concept has been around for quite a while.”
“Mechanical devices aren’t your specialty,” observed Charlotte. “But I’m surprised that the possibility didn’t occur to Hedley.”
“That’s the challenge with new ideas—until some brilliant inventor makes a sudden momentous connection and proves them to be of practical use, they float around outside the parameters of conventional thinking.” Wrexford blew out his breath. “Hedley’s focus is on steam engines and how they can propel a traditional wheel, which has existed for millennia. It simply never occurred to him to imagine a new type of engine combined with a propeller to create a propulsion system capable of moving a ship through water.”
Charlotte, too, was carefully examining the illustrations. “Good heavens!” She pointed to the sketch of a flying machine powered by a screw-shaped device. “So it looks as though the stolen da Vinci manuscript may have some relevance to the concept of nautical propulsion!”
“Yes, there is some theoretical relevance,” agreed Wrexford. “I’m no expert, but having skimmed through some of the explanations in these books, it appears that a number of thinkers throughout history have experimented with the scientific principles behind a screw mechanism like the propeller and how its spinning could be used to force fluid—such as water or air—in one direction and thereby create thrust in the opposite direction.”
He opened another book and displayed an engraving of a primitive device. “One of the earliest examples of a practical screw mechanism was designed by Archimedes, one of the great scientific minds of ancient Greece. He designed a revolving device—known as the Archimedes screw—that moved water from one level of elevation to a higher one.” He snapped the pages shut. “There’s da Vinci, of course, who was clearly studying turbulence in water and in air with the idea that it was a force that could propel objects. And then our own Robert Hooke, who in 1680 observed that the vanes of a windmill were capable of moving water.”
“Bernoulli—” began Cordelia.
“Bernoulli suggested using vanes—or blades—as a means of propelling boats through water, and even did some calculations on the optimal angles of the vanes for creating maximum thrust,” interjected Wrexford. “He was mainly interested in the theory and mathematics of fluid motion rather than any practical application. However, he did realize the ramifications.”
The earl then tapped a finger to the open book showing a primitive submarine. “Then we come to the journal that Peregrine discovered among the bundle of new scientific books sent from Hatchards. It shows an ingenious nautical invention created by an American student named David Bushnell in 1776, which used a propeller to move his underwater craft through the water.”
Charlotte crouched down for a closer look. “It truly does look like an ordinary screw, magnified many times.”
“Maudslay’s lathes revolutionized the production of screws, making it possible to mill very precise threads in metal,” said Sheffield.
“Which makes me wonder whether his work on a nautical propulsion system involved the idea of a propeller,” said Wrexford.
“By God, you might be right. Maudslay never actually told me anything about the details of his work.” Sheffield’s jaw clenched for an instant. “So you think this proves that Taviot’s consortium was behind the fire at Maudslay’s laboratory so they could steal his idea?”
“Or it’s possible that the government stole Maudslay’s technical drawings first,” suggested Charlotte. “And that Taviot’s consortium then stole them from the naval laboratory at the King’s Dockyard.”
“That’s pure speculation,” replied the earl.
“Remember, I did notice strange curves—which now make perfect sense—on the technical documents I saw at the King’s Dockyard,” pointed out Charlotte. “So however Tilden and his fellow engineers came up with the idea, I am sure they were working on designs for a propeller.”
She frowned in thought. “Their steam engine prototype looked radically different . . .”
“That’s because it needs to power a crankshaft in order to turn a propeller,” said the earl. “Never mind the detailed mechanics right now, but in a nutshell, you need to redesign the traditional steam engine for nautical use.”
Cordelia was looking at one of the other open books. “It says here that the American inventor Robert Fulton was also experimenting with propellers in America. It stands to reason that Maitland was aware of this and may even have worked with Fulton on the idea.”
“That makes sense,” agreed Wrexford. “I’ll also point out that James Watt experimented with a propeller design featuring four angled blades rather than a screw-type device when he began exploring the idea of steam-powered boats. But he abandoned the idea and stuck with paddle wheels.” He held up yet another book. “And a man by the name of Stevens built a prototype steamboat with a propeller in 1804. It fared well in test runs, but interest in the technology never seemed to gain momentum.”
“An idea ahead of its time?” mused Sheffield.
“Some entrepreneur will likely make a fortune when the moment is right,” replied the earl.
“That brings us back to our two fundamental questions,” said Charlotte. “We now feel certain that we can prove Taviot is responsible for a past betrayal of our country during wartime, a terrible act that led to the death of Wrex’s brother and countless other fine men, as well as the recent murder of Neville Greeley. But as for whether the consortium is, in fact, a fraud . . .”
She looked to Wrexford. “That now seems less clear.”
