Evangelista Torricelli was a gifted Italian physicist and mathematician. He was the first person to create a sustained vacuum and he invented the barometer. An excellent mathematician, his work in geometry helped towards the discovery of integral calculus in the mid-seventeenth century. He was also a skilled lens grinder, making quality telescopes and microscopes. The torr (symbol: Torr), a unit of pressure, is named in his honor.

### Early Life:

Evangelista Torricelli was born on 15th October 1608 in Rome to Gaspare Ruberti, a textile worker and Caterina Angetti. He was the eldest of three brothers; his parents were of modest means. Evangelista was educated in Faenza by his uncle, Brother Jacopo. Evangelista then entered a College in 1624, studying mathematics and philosophy. Showing great ability, in 1626 he was sent to Rome for further studies in mathematics, hydraulics, mechanics and astronomy under Benedetto Castelli’s direction.

### Career:

Torricelli became an admirer of Galileo’s astronomy work and corresponded with him. However as Galileo’s views clashed with the Catholic Church, Torricelli decided to concentrate on mathematics rather than astronomy.

In 1633 Torricelli was appointed as secretary to Giovani Ciampoli, a friend of Galileo, a position he kept for nine years. During this time he completed much of the work for “Opera Geometrica” which would be published in 1644.

Torricelli became Galileo’s assistant in 1641 during the last few months of Galileo’s life. In 1642, Torricelli was appointed as successor to Galileo, becoming court mathematician to Grand Duke Ferdinando II of Tuscany. The position included lodgings at the Medici palace in Florence and paid a good salary. Torricelli held this position until his death.

### Contributions and Achievements:

Torricelli made advancements in mathematics, improving upon Bonaventura Cavalieri’s “theory of indivisibles” by extending this theory to cover curved indivisibles. He calculated the areas and the center of gravity of the cycloid. His findings laid the groundwork for integral calculus which was discovered independently by Isaac Newton and Gottfried Leibniz later on in the century. In 1644 he published a three part work Opera Geometrica (Geometric Works).

In fluid dynamics, he discovered “Torricelli’s theorem”. It states that the flow of liquid through an opening is proportional to the square root of the height of the liquid.

He studied the properties of the geometric figure now called “Torricelli’s trumpet” which has infinite surface area but finite volume.

Torricelli also studied the parabolic motion of projectiles, giving a theory for projectiles launched at any angle. He put his calculations to practical use, supplying numerical tables to gunners so they could find the correct elevation for their guns for each required range.

The most important of his inventions was the mercury barometer, which he devised while investigating the maximum suction abilities of water pumps. Torricelli carried out experiments using heavier and heavier liquids, resulting in an experiment that created a sustainable vacuum, using mercury, with a glass tube roughly one meter long. This experiment led to the development of the barometer.

An excellent instrument maker, Torricelli ground lenses with such accuracy that he produced some of the finest telescopes and microscopes of that time.

### Other Interests and Death:

In Florence, Torricelli made friends with painter Salvatore Rosa, Hellenist Carlo Dati and the hydraulic engineer Andrea Arighetti and he wrote a number of comedies, which have sadly not survived.

Torricelli died on 25th October 1647 in Florence aged 39 from typhoid and was buried at the Basilica of San Lorenzo. The torr (symbol: Torr), a unit of pressure, is named in his honor.