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René Grillet de Roven: The Watchmaker Who Revolutionized Portable Computing


In the annals of computing history, the name René Grillet de Roven may not be as well-known as those of Charles Babbage or Alan Turing, but his contributions to the field of mechanical calculation were no less significant. As a skilled watchmaker and mechanician in 17th-century France, Grillet created a remarkable portable calculator that combined the best of existing technology with his own innovative ideas, paving the way for the development of modern portable computing devices.

The Watchmaker‘s Art and the Birth of Mechanical Computation

The connection between watchmaking and early computing may not be immediately apparent, but upon closer examination, the two fields share many commonalities. Watchmakers, like Grillet, possessed an intimate understanding of gears, springs, and other mechanical components, as well as a keen eye for precision and detail. These skills proved invaluable in the creation of early calculating machines, which relied on intricate mechanisms to perform arithmetic operations.

Grillet was not alone in his pursuit of mechanical computation. Other notable watchmakers, such as Blaise Pascal and Gottfried Leibniz, also made significant contributions to the field. Pascal‘s calculating machine, the Pascaline, utilized a series of gears and dials to perform addition and subtraction, while Leibniz‘s Stepped Reckoner expanded on this concept to include multiplication and division.

Watchmaker Calculating Machine Year
Blaise Pascal Pascaline 1645
Gottfried Leibniz Stepped Reckoner 1672
René Grillet de Roven Portable Calculator 1673

The Portable Calculator: A Marvel of Ingenuity

Grillet‘s portable calculator, described in his 1673 book "Curiositez mathematiques de l‘invention du Sr Grillet horlogeur a Paris," was a true marvel of ingenuity. By combining the wheels of Pascal‘s calculator with the cylinder of Petit‘s "cylindre arithmetique," Grillet created a device that was compact, versatile, and capable of performing all four arithmetic operations.

The calculator consisted of a wooden box measuring just 14.5 cm by 32.5 cm by 5 cm and weighing a mere 990 grams. On the lid of the box were 24 sets of wheels, arranged in three rows of eight, each composed of several concentric circles. These wheels allowed for the input and display of numbers, while the bottom of the box housed a set of cylindrical Napier‘s bones, which aided in the calculation of partial products during multiplication.

To perform a calculation, the operator would set up the first number on the upper row of wheels, the second number on the middle row, and mentally perform the operation, setting down the digits of the answer on the lower row. The cylindrical Napier‘s bones in the lower part of the machine would then be used to calculate the partial products, which could be added up using the wheels on the lid.

The Quest for Commercialization and the Importance of Intellectual Property

Grillet‘s portable calculator was not just a technological achievement; it was also a commercial venture. The inventor went to great lengths to keep the inner workings of his machine a secret, even going so far as to charge curious onlookers a silver coin to witness its operation at fairs in Paris and Amsterdam.

However, despite Grillet‘s efforts to commercialize his invention, the calculator did not achieve widespread success. The high cost of production, the complexity of the machine, and the limited demand for such devices in 17th-century Europe all likely contributed to its limited uptake.

Grillet‘s story also highlights the importance of intellectual property protection in fostering innovation. The seizure of his book by the Intendant of Police in Paris, possibly due to privilege infringement, underscores the challenges faced by inventors in an era when patent laws were not well-established.

Country First Patent Law Year
Venice Venetian Patent Statute 1474
England Statute of Monopolies 1624
United States Patent Act 1790
France Law on Patents 1791

The Evolution of Portable Computing Devices

Grillet‘s portable calculator may have been ahead of its time, but it was not the end of the story. Over the centuries that followed, inventors and engineers continued to push the boundaries of what was possible with portable computing devices.

One of the key milestones in this evolution was the development of the microprocessor in the 1970s. This tiny chip, which contained thousands of transistors, allowed for the creation of much smaller and more powerful computing devices. The first pocket calculator, the Cal Tech, was released in 1970, and by the end of the decade, these devices had become commonplace.

The 1980s and 1990s saw the rise of personal digital assistants (PDAs), such as the Apple Newton and the Palm Pilot, which offered a range of features beyond simple calculation, including calendars, address books, and note-taking capabilities. These devices paved the way for the smartphones and tablets that have become ubiquitous in our modern world.

Year Device Manufacturer
1970 Cal Tech Pocket Calculator Texas Instruments
1984 Psion Organizer Psion
1993 Apple Newton Apple
1996 Palm Pilot Palm Computing
2007 iPhone Apple
2010 iPad Apple

The Art and Aesthetics of Early Calculating Machines

In addition to their technological significance, early calculating machines like Grillet‘s were also objects of beauty and craftsmanship. The intricate gears, dials, and mechanisms of these devices were often housed in elegantly designed cases, with decorative elements that reflected the artistic sensibilities of the time.

The two surviving examples of Grillet‘s calculator, housed in the collection of the Musée des Arts et Métiers in Paris, offer a glimpse into the aesthetic considerations that went into the design of these early machines. The use of materials like wood, brass, and glass, as well as the precise arrangement of the wheels and cylinders, create a sense of harmony and balance that is both functional and visually appealing.

Grillet's Portable Calculator
One of the two surviving examples of René Grillet de Roven‘s portable calculator, housed in the Musée des Arts et Métiers in Paris. (Image credit: Musée des Arts et Métiers)

The Legacy of René Grillet de Roven

Although René Grillet de Roven‘s name may not be as well-known as some of his contemporaries, his contributions to the field of mechanical computation and the development of portable calculating devices cannot be overstated. His innovative design, which combined the best of existing technology with his own unique ideas, laid the foundation for the portable computing devices that have become an integral part of our modern lives.

Today, researchers and scholars continue to study the work of early inventors like Grillet, unearthing new insights and reinterpreting their contributions in light of our current understanding of computing and technology. The preservation and study of these early calculating machines, through institutions like the Musée des Arts et Métiers, ensure that the legacy of these pioneering inventors will endure for generations to come.


The story of René Grillet de Roven and his portable calculator is one of innovation, perseverance, and the enduring human fascination with the power of mathematics and mechanical computation. By combining his skills as a watchmaker with his passion for mathematics, Grillet created a device that was both technologically significant and aesthetically beautiful, paving the way for the development of modern portable computing devices.

As we continue to push the boundaries of what is possible with technology, it is important to remember the pioneers like Grillet who laid the foundation for our current achievements. Their stories serve as a reminder of the ingenuity, creativity, and determination that have always been at the heart of human progress, and an inspiration for the innovators of tomorrow.