The Wheel of Knowledge – a revolutionary mechanism by Agostino Ramelli (12 photos + 1 video)
The e-book has become the greatest invention since Gutenberg's printing press. While the printing press made books accessible, the e-reader has compressed them to such an extent that we can easily carry thousands of editions with us. 
To someone in the 16th century, such a concept would have seemed fantastical, but it nevertheless occurred to contemporaries. In particular, to Agostino Ramelli. 
Book Wheel from Agostino Ramelli
Agostino Ramelli was an Italian military engineer. In his youth, he served under the renowned condottiere, the Marquis of Marignano, and received training in mathematics and military engineering. Ramelli had a gift for solving technical problems, and as his reputation grew, he went to France to serve the Duke of Anjou, the future King Henry III. When, during the siege of La Rochelle, Ramelli successfully engineered an undermining of a bastion and helped breach the fortifications, he gained the commander's special favor. 
Agostino Ramelli
Agostino Ramelli didn't create many machines. But he had a wealth of ideas for solving everyday problems, such as grinding grain, moving heavy loads, digging ditches, and defending cities. In 1588, he collected about two hundred of his best designs and published a book, "Le diverse et artificiose machine del Capitano Agostino Ramelli"—"The Various and Artful Machines of Captain Agostino Ramelli." 
The book contained 195 engravings with detailed descriptions of each mechanism in Italian and French. Ramelli devoted half the work to various methods of raising water, such as pumps, water wheels, and wells. Other drawings included cranes, bridges, fountains, cofferdams, jacks, projectiles, and so on. One of the most famous designs in the book was the book wheel. 
The book wheel was Ramelli's attempt to solve the problem of reading or comparing multiple books simultaneously. Printed editions of the era were typically large and heavy, making it virtually impossible to access multiple volumes unless they were spread out on a large table and turned the pages with one's foot, which, as Ramelli noted, was quite inconvenient for those "unwell and tormented by gout." 
The book wheel resembled a Ferris wheel at an amusement park, with tilting book stands instead of gondolas. A complex system of gears known as planetary gearing, previously used only in astronomical clocks, ensured that the book surfaces maintained the same angle regardless of the wheel's position. 
A seated reader used a hand or foot mechanism to turn the wheel and bring the desired volume to them. Gravity, like a Ferris wheel, would have been sufficient to hold the music stands level, but Ramelli wanted to demonstrate his mathematical prowess, which led to an unnecessarily complex design. 
Ramelli intentionally made his designs complex to demonstrate the application and importance of mathematics and geometry in engineering. In the preface to his book, he made no attempt to hide this fact. He wrote: "On the Excellence of Mathematics, which shows how necessary mathematics is for the comprehension of all the liberal arts." 
Ramelli never built any of his machines, but his illustrations had a profound influence on the development of mechanics. The only mechanism that was actually implemented, albeit generations later, in the 17th and 18th centuries, was the book wheel. Dozens of book wheels based on Ramelli's designs were built throughout Europe. At least fourteen of them survive to this day. 
