Joseph Sauveur facts for kids

Joseph Sauveur (born March 24, 1653 – died July 9, 1716) was a French mathematician and physicist. He taught mathematics and became a member of the French Academy of Sciences in 1696.

Early Life and Challenges

Joseph Sauveur was born in La Flèche, France. His father was a local notary. Joseph faced a big challenge: he couldn't hear or speak at all until he was seven years old. Despite this, he received a good education at the Jesuit College of La Flèche.

When he was seventeen, his uncle offered to pay for him to study philosophy and theology in Paris. However, Joseph discovered the works of Euclid, a famous mathematician, and became very interested in anatomy and botany instead.

Life at Court and Early Work

Joseph soon met Cordemoy, who worked for the son of King Louis XIV. Cordemoy was impressed by Joseph and told others about his talents. Even with his hearing and speech difficulties, Joseph began teaching mathematics to young princes and pages at the royal court. One of his students was Eugene of Savoy, a famous military leader.

By 1680, Joseph was well-known at court. He taught anatomy to courtiers and even calculated the odds for a card game called "basset."

In 1681, Joseph Sauveur helped with a waterworks project for the estate of the "Grand Condé" at Château de Chantilly. He worked with Edmé Mariotte, who is known as the "father of French hydraulics." Condé liked Sauveur very much and protected him from anyone who made fun of his speech. Sauveur often stayed at Chantilly, where he worked on hydrostatics, which is the study of how liquids behave when they are still.

Teaching and Music

In the summer of 1689, Sauveur was chosen to teach science and mathematics to the Duke of Chartres, who was King Louis XIV's nephew. For the prince, he wrote a book about the basics of geometry. He also worked with Marshal Vauban on a book about military forts. Sauveur and Chartres were even present when the French army attacked the city of Mons in 1691.

Another teacher for the prince was Étienne Loulié, a musician. Loulié taught music theory. Sauveur and Loulié worked together to show the prince how mathematics and music were connected. Parts of their lessons can still be found in Sauveur's writings on music theory and Loulié's book, Éléments. In the years that followed, Sauveur taught mathematics to other royal family members.

In 1686, he became a mathematics professor at the Collège de France. Because of his speech, he was allowed to read his first lecture instead of reciting it from memory.

Discovering Acoustics

Around 1694, Sauveur started working with Loulié on "the science of sound," which we now call acoustics. A writer named Fontenelle said that Sauveur planned to "discover an unknown country" in sound, creating his "own empire" in the study of "acoustical sound."

Fontenelle also pointed out something amazing: "He had neither a voice nor hearing, yet he could think only of music. He had to borrow the voice and ear of someone else, and in return, he gave musicians new discoveries." The Duke of Chartres helped him a lot with this work.

Sauveur's research led to "a new musical language that was more useful and broader." He also created a new system for sounds, a special monochord (a tool for studying musical pitch), and an échomètre. He studied "fixed sound" (which means absolute frequency) and how strings vibrate. His work even led him to study the music of ancient Greeks, Romans, Arabs, Turks, and Persians.

Sauveur's Contributions to Acoustics

Sauveur is most famous for his detailed studies on acoustics. He is even credited with inventing the word acoustique, which comes from an ancient Greek word meaning "able to be heard."

His work involved studying how frequency (how fast something vibrates) relates to musical pitch (how high or low a sound is). He researched things like vibrating strings, how to tune instruments, harmonics (extra sounds that make a note richer), and the ranges of voices and musical instruments.

He also created a way to measure musical intervals within an octave. While Marin Mersenne's theories from 1637 were correct, his measurements weren't very exact. Sauveur greatly improved Mersenne's calculations by using acoustic beats (when two sounds close in pitch create a pulsing effect) and metronomes (devices that keep time).

Sauveur used special terms for tiny divisions of an octave, like:

• méride: 1/43 of an octave.
• eptaméride: 1/301 of an octave, or 1/7 of a méride. This term later became known as a savart.
• A division of 1/55 of an octave became known as a "Sauveur comma."

Challenges with Musicians

In 1696, Sauveur was elected to the French Royal Academy of Sciences. Most of his work on acoustics happened while he was a member. However, he faced a big problem: the musicians who were helping him with his experiments became frustrated. They found his new measuring units too small for the human ear to tell apart and too hard for the human voice to sing.

They also didn't like the "equal tuning" he suggested for instruments. This was a system where all musical intervals were exactly the same size, which was different from how musicians usually tuned their instruments. They also didn't like his new names for musical notes, like pa and ra, which were supposed to replace the familiar ut, re, mi, fa, sol. Sauveur had divided the octave into 3,010 tiny parts!

Around 1699, Sauveur and the musicians had a disagreement, and he found it hard to finish some of his experiments. Loulié, his former collaborator, had already started his own path by 1698, publishing a book called the Nouveau Sistème, which showed their work from a musician's point of view.

In 1701, Sauveur finally presented his research results to the Academy. He criticized Loulié's practical inventions for not being scientific enough. For example, Loulié had invented a metronome-like tool called the "chronomètre" in 1696. Sauveur pointed out that Loulié's invention wasn't based on the second and its pendulum swings weren't linked to a specific note value, unlike his own échomètre.

Sauveur also presented his own monocorde for tuning harpsichords. It was based on his "new system" of dividing the octave into tiny, equal units. He compared it to Loulié's sonomètre, which the Academy had approved in 1699. Loulié's device copied the unequal musical intervals that were actually used in France at the time.

Joseph Sauveur was described by someone who knew him as "very helpful, gentle, and without humor." He was declared a "pensioned veteran" of the Academy on March 4, 1699. He passed away in Paris in 1716.

See also

• Magic square
• Mersenne's laws
• Sauveur pitch

Images for kids

• 

  Front page of Geometrie élémentaire et pratique (1753) by Joseph Sauveur, edited and added to by Guillaume Le Blond