Four Facts About Tito Gonnella’s Adding Machines

Black and white sketch of one of Tito Gonnella’s first adding machines.
  • Tito Gonnella invented a dial adder and keyboard adding machine.
  • His keyboard adder made some improvements on the design and is known as one of the seventh keyboard-driven machines.
  • He received a bronze medal at the 1851 London International Exhibition for his keyboard adding machine.
  • Tito Gonnella is also known as the inventor of a reflecting telescope, first presented in 1841.

Tito Gonnella’s Adding Machines History

The dial adder was designed for simple calculations and was prone to jamming.

The Italian scientist and inventor Tito Filippo Gonnella (1794–1867), professor of mathematics and mechanics at the Florentine Accademia di Belle Arti di Firenze, is primarily known as the inventor (in 1824) of one of the first planimeters in the world. He’s also known for his work on other inventions, like an improved reflecting telescope in 1841.

Tito Gonnella donated a dial adder to the Grand Duke of Tuscany, a founder of his research.

Tito Gonnella created two adding machines that are still significant in the history of calculators: a dial adder and a keyboard adder. The dial adder, or the wheel adding machine, was similar to an earlier invention by PascalJean Lépine and Hillerin de Boistissandeau created similar machines in the 1720s, as did David Roth in the 1840s.

Quick Facts

c. 1850s
Tito Gonnella
Original Use
Adding machine innovations

The keyboard adding machine is considered the seventh keyboard-driven machine built at the time. Some machines were invented and built in the United States, so there’s reason to believe Gonnella wasn’t aware of these. Others, however, were built in Europe and shown at the London International Exhibition, making it likely Gonnella was familiar with them.

Tito Gonnella’s Adding Machines: How They Worked

Users of the keyboard adder could only add a single digit at a time for calculations.

Both mechanical calculator devices came with some critical issues, but they are still significant devices in the history of calculating machines. Gonnella’s dial adder was a six-positional brass and iron device contained in a wooden box. It used a pen to enter the numbers. While it worked for many simple calculations, the unique tens carry transfer mechanism was prone to jamming. This continued even after Gonnella created an anti-jamming device.

The solid brass-iron keyboard adder used a nine-digit keyboard and a helical drum for the accumulator. It wasn’t as fast as other adding machines of its time and required users to add a single digit at a time. The keyboard keys were attached to sectors with the corresponding number of teeth. This allowed each key to rotate the correct dial the appropriate revolutions to perform the calculation.

Tito Gonnella’s Adding Machines: Historical Significance

The keyboard adder and dial adder needed many improvements to make them practical for users.

While both mechanical calculator inventions were innovative, they didn’t offer the practicality they needed to be commercial successes. Both of Tito Gonnella’s adding machines were subject to key issues. The dial adder tended to jam during ripple carry cases. For example, when the user tried to add one to 9,999.

The keyboard adder needed a mechanism for resetting the drum and a spring-driven arm to prevent the wheels from recoiling. It could also use a five-key design to streamline the machine. A five-key keyboard would have keys that could be pressed two in a sequence to add digits greater than five.

Tito Gonnella’s Adding Machines Explained – Everything You Need To Know FAQs (Frequently Asked Questions) 

When were Tito Gonnella's Adding Machines invented?

The exact date is unknown, but the dial adder was first presented in 1857. The keyboard adder was first presented in 1858.

What were Tito Gonnella's Adding Machines?

These two machines worked as mechanical calculator devices. They assisted in addition calculations and helped lead to more complex calculation machines.

Who is Tito Gonnella?

Tito Gonnella was a professor of mathematics and mechanics at the Florentine Accademia di Belle Arti di Firenze. He’s best known as an inventor.

Why did Tito Gonnella invent the adding machine? 

As a professor of mathematics and mechanics, Gonnella is believed to have created these machines as a way to advance the field and improve the adding machine technology.

What does Tito Gonnella’s adding machine do?

Both adding machines allow for numbers to be added to perform calculations.

Is Tito Gonnella’s adding machine still in use?

Tito Gonnella’s machines were primarily used for research purposes. They weren’t sold commercially and very few are known to still exist.

Where can I buy Tito Gonnella’s adding machine?

Very few calculators were made, making any adding machine by Tito Gonnella extremely rare. They aren’t currently for sale for commercial use.

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