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No. 1535:
Inventing the Clock

Today, we invent the mechanical clock. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

I've remarked before how hard it is to date the first mechanical clocks. Old manuscripts start hinting at them in the late 1200s, but we find no clear picture of a clock until a century later. One hint was dropped by the poet Dante in the early 1300s. He said :

As clock, that calleth up the spouse of God ...
Sends out a tinkling sound, of note so sweet, ...
Thus saw I move the glorious wheel; ...

That's no older water clock. Dante had to've been touched by the rhythmic escapement mechanism and turning gears of the new mechanical clocks. Historian Jean Gimpel describes the free-wheeling medieval view of invention that finally gave us mechanical clocks:

In a burst of intellectual optimism Gilbert of Tournay cried, "The truth is open to all, for it is not yet totally possessed." Bernard of Chartres said, "We are as dwarfs mounted on the shoulders of giants." That was six hundred years before Newton changed it slightly. Bernard was telling us what we could do. When Newton changed we to I, it turned from a remark about possibility into a boast about his own accomplishments.

Medieval inventors turned their optimism into a sun spray of creativity: They made Gothic cathedrals, fully-evolved manuscript books, crossbows, eyeglasses, water-power systems. And in the mid-13th century they started thinking about machines that could point at the moving sun throughout the day. Not exactly a clock, though that's what the face of your clock really does today. In 1271, a writer called Richard the Englishman issued a tantalizing report:

Clockmakers [he said] are trying to make a wheel which will make one complete revolution for every equinoctial circle ... The method of making such a clock would be this, that a man make a disc of uniform weight ... Then a lead weight should be hung from the axis of the wheel, so that it would complete one revolution from sunrise to sunrise...

Richard leaves us to wonder how they made a wheel unwind just one revolution in a day. Was it to be a very heavy wheel with a very small spindle? Perhaps the idea had yet to be worked out. Or maybe Richard had seen one of the new clock escapement mechanisms and had not fully understood it.

Mechanical clocks were clearly being made by the early 1300s. Yet not till 1364 did an Italian clock-maker named Giovanni di Dondi write a proper treatise on his craft. Giovanni's father Jacopo di Dondi was a clockmaker who'd built the earliest tower clock in Padua in 1344.

Lewis Mumford said of the clock that it was "the key machine of the modern industrial age." He called the appearance of this first automatic machine a prophecy that "marks a perfection towards which other machines aspire." What Dante had called the glorious wheel was the doorway into our age of precision machines and high technology.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Gimpel, J., The Medieval Machine. New York: Penguin, 1977. (See especially, Chapter 7.)

The passage from Canto X of Dante's Paradiso goes as follows:

To win her Bridegroom's love at matin's hour,
Each part of other fitly drawn and urged,
Sends out a tinkling sound, of note so sweet,
Affection springs in well-disposed breast;
Thus saw I move the glorious wheel; thus heard
Voice answering voice, so musical and soft
It can be known but where day endless shines.

For more on the origins of clocks see Episodes 1506, 1307, and 1417.

di Dondi's clock

di Dondi's clock