Leonardo Da Vinci's clock experiments - 150 years ahead of his time

The versatile Renaissance artist Leonardo da Vinci also dealt with clocks and time measurement

Codex Madrid I contains at least 60 sketches, drawings, and passages of text that directly or indirectly relate to the construction of clocks. Leonardo not only characterizes the state of knowledge of his time but also invents his own mechanisms.

His diverse involvement with mechanical elements and his fundamental understanding of their function led him, after some experience, to the design of clocks controlled by gravity pendulums. Whether he actually built such clocks or had them made by craftsmen is unknown.

In any case, he knew all the components required for this, partly developed them himself and thus, as a visionary, also in the field of time measurement, he was ahead of his era.

However, the actual breakthrough of the pendulum clock principle only came with the work of the Dutchman Christian Huygens over 150 years later.

The oldest mechanical clocks (so-called wheel or balance clocks) date back to the 13th century. These clocks work according to the following principle:

The balance or Foliot 4 consists of a balance beam mounted horizontally on a spindle, the period of oscillation of which can be changed by means of movable weights.

Attached to the spindle are two metal tabs that alternately engage the teeth of the toothed crown wheel, driven by a clock weight or a tensioned spring. On the one hand, the crown wheel continuously imparts impulses to the balance, keeping it in constant oscillation;

On the other hand, the crown wheel is inhibited by one of the two lobes on the spindle after each half oscillation of the balance (hence the term "escapement"). In principle, the rate of the watch would be determined by the rotation of the crown wheel.

However, this rotation is interrupted by the escapement and the balance mechanism, so that the rotation of the crown wheel slows down and at the same time the time is divided into regular intervals, the sum of which is finally used to indicate the time via a gear train using hands.

Historically, it was only the invention of the escapement with balance (or foliot) that made the mechanical clock possible.

The other components, such as the weight drive, gears and rotating hands, were already known. Whoever invented this type of clock with scales in the 13th century
It is not known who found it.

As a variant of the beam balance, a back-and-forth swinging wheel was often used , which is called a "balance wheel" 5

Leonardo da Vinci draws and describes a clock with a foliot in detail in Codex Madrid I, foglio 115 verso, and thereby characterizes the state of knowledge of his time.

Leonardo's improvements:

Leonardo's preoccupation with clocks is manifested above all in the manuscript of the Codex Madrid I, which can be considered his fundamentally mechanical textbook. At least 60 sketches and drawings, and almost as many text passages refer directly or indirectly to the construction of clocks, as well as to the construction and functioning of individual components.

But Leonardo's creative mind didn't stop at describing the watchmaking art of his era. He soon began devising his own modified clockworks.

A first variant appears to be the rather complex design of a gear clock including a display in Codex Madrid I, leaf 27 verso. Another very interesting example can be found in Codex Madrid I, leaf 157 verso.

This clock, designed as a balance wheel, contains improved elements, such as a double reduction of the weight drive over two stages to extend the duration of the drive, and a vertically mounted balance wheel (vane wheel).

This Leonardo-style clock appears very distinctive and original. A clever mechanism with a pinion and a fixed, sinusoidally notched roller replaces the conventional escapement. The pinion and spindle, which moves in a wave-like manner within the notch, allow the drive to interact with the balance.

The escapement function is performed by the interplay of a notched roller and a rocking spindle. The balance rotates alternately from left to right and vice versa.

A small crank, mounted in the direction of the roller's axis, serves both to wind the clock and to adjust it. However, such a construction is certainly very imprecise, although it is functional in principle.

This is due to uncontrollable frictional forces in the escapement device according to Leonardo.

This means that despite two potential improvements, this wheel clock with balance and escapement according to Leonardo has considerable deficiencies, which Leonardo probably recognized soon enough or even discovered through practical experiments.

The balance is of course not a timekeeper, i.e. no independently oscillating mechanism whose quality or accuracy contributes anything to ensuring correct timekeeping.

Only such an element, which is taken for granted today, makes a watch a real
device for measuring time

Based on the notes scattered throughout Leonardo's writings, as well as the fact that watches are a constant theme for Leonardo, it can be assumed that Leonardo, with great intuition, soon began to look for something better.

Leonardo designed another wheel clock in Cod. Forster II, f. 63. Such a "wheel clock with pendulum," inspired by Leonardo's drawing, can even be purchased today on the clock market, but represents a very far-reaching interpretation of Leonardo's sketch.

 
Using the pendulum as a timepiece is probably not an original idea of ​​Leonardo's; earlier generations had already used handheld pendulums 12 for measuring short-term events, such as in ballistic shooting. Leonardo describes such an experiment, for example, in Codex Madrid I, leaf 147 r.

It is therefore not surprising that Leonardo soon considered using a pendulum to regulate the escapement on the crown wheel of a gear clock. Two corresponding sketches are contained in Codex Madrid I, leaf 61 v.

Further sketches can be found in the Codex Atlanticus, 397 AD. But perhaps Leonardo's true creative achievement lies precisely in this combination of two well-known principles, namely the wheel clock and the self-oscillating perpendicular.

It is conceivable that Leonardo was attempting to eliminate the deficiencies of his own invention. The balance mechanism in the sine-groove design was to be replaced by a pendulum that could interact with the rest of the clockwork via the groove.

The crank then serves the same purpose. However, although the theoretical rationale behind the improvement is sound, the practical success of incorporating such an element into Da Vinci's clock may have been disappointing.

This does not eliminate the problems associated with frictional inhibition.

Leonardo didn't stop at this approach. Scattered throughout his surviving manuscripts are the crucial elements needed to construct a truly successful pendulum clock.

This becomes clear when one compares the sketches and designs by his hand with the reconstruction of a functional model of the pendulum clock, as Galileo Galilei imagined it.

A functional model of this so-called "pendulum clock according to Galileo" is located in the Mueseo Galileo in Florence, which can also be visited as a virtual museum

Galileo's son Vincenzo and Vincenzo Viviani are the only contemporary manuscripts

Source: Fritz Heininger, horologium.at