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Five Machines That Changed the World

Mark Denny

Publication Year: 2007

Ingenium is medieval English vernacular for “an ingenious contrivance.” In this fascinating book, physicist Mark Denny considers five such contrivances—the bow and arrow, the waterwheel, the counterpoise siege engine (including the trebuchet), the pendulum clock anchor escapement, and the centrifugal governor—and demonstrates how they literally changed the world. Interweaving an entertaining narrative with diagrams, equations, and drawings, Denny shares the history of each device, explains the physics behind it, and describes how it was used, how it evolved, and why it is significant in today's world. Consider the bow and arrow, which transformed warfare by allowing soldiers to attack their enemies at a safe distance. Or the waterwheel, which enabled Old World civilizations to grind grain, pump water, and power machines during a period of extreme labor shortages. Medieval warriors engaged in an early form of biological warfare by using the trebuchet to launch dead animals or plague-ridden corpses over enormous fortress walls. The pendulum clock forever enslaved modern humans to the clock by linking the accurate measure of time to the burdens of schedules, deadlines, promptness, and tardiness. And the centrifugal governor gave rise to an entire branch of modern engineering science: feedback control. Reflecting on the inventors of these ancient machines and the times in which they lived, Denny concludes with thought-provoking observations about inventors, inventiveness, genius, and innovation. Whether you dream of making a better mousetrap or launching pumpkins into the stratosphere, Ingenium will tickle your fancy.

Published by: The Johns Hopkins University Press


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pp. vii

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pp. ix-x

The international nature of the historical machines in this book comes through clearly in this list of people from Europe and North America. I am grateful to each of them for assisting me, in one way or another, in writing the book. ...


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pp. xi

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pp. xiii-xvi

The five machines I explore in this book are technologically simple. They are all mechanical, and the basic idea behind each of them is easily conveyed with a single picture. They are scientifically interesting and historically important. They still impact us today and they also leave less obvious but still discernible historical echoes. ...

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pp. 1-30

The bow is one of our oldest inventions. It was developed, we presume, to enhance our ability to hunt prey that was fleeter of foot than our ancestors, or perhaps was too wily or dangerous to approach within spear range. Whatever the reason, the bow proved so successful that it became nearly universal.1 ...

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pp. 31-60

I place waterwheels and windmills in the same chapter, counting them as one machine for the purposes of this book. Of course, the engineering requirements of waterwheels and windmills are di

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pp. 61-92

Ingenium is medieval English vernacular for “an ingenious contrivance.” In those days the word was used to describe siege engines, those weapons of war designed and widely employed to reduce castles to rubble. The crew (and these engines from the Middle Ages required a large crew) were ingeniators—hence, our modern “engineers.” ...

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pp. 93-126

Modern-day workers are slaves to time. They rush to catch the 7:42 train or the 6:55 bus to their places of employment, then “clock in” to work and “clock out” when they leave. In the evening they watch one variant or another of the game of football on TV at a preordained time. ...

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pp. 127-156

The centrifugal governor (fig. 5.1) is indelibly associated with large industrial machinery, and, in particular, with old-fashioned steam engines. The two flyballs whir around and catch the eye, so that in the confusion of moving parts and metallic noises we see the governor, and pick it out visually ...

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pp. 157-168

I would like to try to assess the inventiveness of the people who developed our five machines, but before doing this it would be useful to place their contributions in context, both technologically and historically. So first I will summarize the whys and whens: why I consider each machine to be a world changer ...


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pp. 169-172


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pp. 173-176

E-ISBN-13: 9780801898464
E-ISBN-10: 0801898463
Print-ISBN-13: 9780801885860
Print-ISBN-10: 0801885868

Page Count: 200
Illustrations: 52 halftones, 23 line drawings
Publication Year: 2007