Evangelista Torricelli, an Italian man, and a physicist by occupation, initially studied at Jesuit schools in Faenza, near Ravenna. He was so good as a Physicist and a Mathematician that he was sent to Rome for further studies under Benedetto Castelli’s direction. Torricelli was introduced to Galileo by Benedetto Castelli and there Torricelli spent his time being Galileo’s assistant and secretary for a last few months of Galileo’s life. After Galileo passed away in January 1942, Torricelli was offered a position as a court mathematician and philosopher, Galileo’s old position, by the Grand Duke of Tuscany. This position was held by Torricelli till his death.
Contributions and Achievements:
Torricelli, also known as the father of hydrodynamics by Ernst Mach, was very famous for his study of the motion of fluids. He also carried out experiments of gases although the term was not invented by then. This led him to invent the Mercury Barometer, most important of his inventions. The invention took place by conducting an experiment on the air pressure and vacuum. Back then, the nature of vacuum was a debatable issue. Aristotle, a Greek philosopher and scientist, believed that vacuum could not exist as he said, “Nature abhors a vacuum.”
On the other hand, Galileo believed that vacuum could exist and he explained the mechanism of the suction in a water pump that it was the vacuum that produced the action, and not the air pressure of the liquid being pumped.
Galileo also felt the air was weightless. The debaters noticed that the suction pumps, regardless of the size and power, in mines could not raise water for more than eighteen bracci which is about 30 feet or 9 m. Why did the water not flow to the maximum if nature really abhorred vacuum? That’s when Torricelli invented the barometer while explaining the phenomenon. Barometer was a great invention in the field of physics of atmosphere and the behavior of gases. He also contributed to meteorology by suggesting wind was caused by differences in the density of air, which is caused by the variations in the air temperature, and not by ‘Exhalations’.
To represent the mechanism of the suction pump in a small tube, he took heavier liquids like honey, sea water and mercury etc. instead of pure water. Torricelli used relatively smaller tubes, which were sealed at one end, for conducting the experiment with mercury. He filled about a meter of such tube with mercury and sealed the open end with his thumb before inverting the tube. He then submerged the tube into the dish of mercury. On inverting, the mercury in the tube dropped half way down and left an empty space at the top and a column of mercury in the tube about one and one-third bracci in height.
The dispute about the nature of vacuum was settled when Torricelli represented the experiment in this way: The weight of air pushing down on the dish of mercury prevented the mercury in the tube from falling out completely and the mercury was not pulled by the mercury. The weight could retain about thirty inches of mercury in the tube. Torricelli observed that such pumps could cause the water to move upwards, by evacuating the air pressure above a column of water, but that the water would move up only as far as the air pressure below pushed it up. The water came to a stop when the weight of the water exceeded the power of the air pressure below no matter how hard the pump worked. This also came to Torricelli’s notice that the height of the mercury varied by the passage of time.
It was due to changes in the air pressure overtime that this happened. A French scientist Marin Mersenne (1588-1648) visited Torricelli in 1644 and took with him the idea of mercury barometer to his friend Blaise Pascal. Pascal also agreed to the fact that the air pressure and the altitude were inversely proportional. It was shown by Pascal practically that the barometric pressure did indeed decrease as one ascended a mountain. This showed that Torricelli’s theory was absolutely correct.
Vincenzo Antinori drew an analogy a few years later that Torricelli’s invention of Barometer was to Physics what the invention of telescope was to Physics. Torricelli had also made improvements to the telescope which was an instrument used by Galileo for astronomy. Torricelli could grind lenses with such accuracy that he produced some of the finest telescopes.
Torricelli contributed a great deal to the field of mathematics which was an important contribution in the scientific history. He worked on the equations of curves, solids, and their rotations to fill in the missing parts between the Greek geometry and Calculus based on the works Francesco Cavalieri’s “of indivisibles. Calculus was given its first complete formulation by Isaac Newton and Gottfried Wilhelm Leibniz, along with the works of René Descartes, Pierre de Fermat, Gilles Personne de Roberval and others.
Torricelli carried on with the tradition of Italian scientific pioneering, although he was not as good as his older contemporary Galileo. The tradition did not last long after his death and by the mid of seventeenth century or the beginning of the next century, Northern Europe had become the center of scientific progress.