# Daniel Bernoulli

**Early Years and Following**

Daniel Bernoulli was born on February 18 at the turn of the 18^{th} Century. He was born in Groningen, Switzerland to Johann Bernoulli and Dorothea Faulkner. As it turned out, mathematics seemed to be the predominant are of study for much of the Bernoulli family. Money was not a problem in the family as his father, Johann, was a medical physician and his mother, Dorothea, came from a high society family in Basel.

Besides being a physician, the older Bernoulli filled the chair as head of mathematics at university in Groningen. He was instrumental in moving forward the latest math discipline of calculus. Johann’s knowledge of math made him a notable in that discipline.

He desperately wanted his son Daniel to enter the world of business, and have a more secure future. When the eldest Bernoulli Nicolaus had refused to enter the business route and pursue mathematics; Johann was reticent of Daniel going that path. He felt Daniel had the capacity to be more in life. Because of the lack of encouragement on the part of his father, Daniel more than gained likely much of his initial knowledge of mathematics from his older brother Nicolaus.

Daniel’s uncle, Jacob Bernoulli was in charge of the mathematics at university in the town of Basel. As mentioned before, math held a major place in the Bernoulli family line. When the time came that Daniel’s uncle Jacob passed away; Johann Bernoulli was invited to take over the head position of math in Basel. Daniel was five years old at this point in time.

In 1713, when Daniel was 13 years of age, Johann had Daniel admitted to University in Basel. His father wanted him to learn anything but mathematics; Daniel ended up studying classics along with logic. Daniel earned his bachelor’s degree by age 15. During the time he was taking these classes; Daniel’s father did provide some education in mathematics, as did his older brother Nicolaus with calculus.

When he earned his master’s degree, Daniel spent a period of time away from college. However, when Johann realized that Daniel had no interest in the business realm; he allowed Daniel to come back to college to learn medicine. If his son was not going to seek a businessman’s life; hopefully he would be inclined towards medicine like himself. Daniel was more inclined to follow that route which pleased Johann immensely.

Now that Johann felt his son Daniel was willing to pursue something with financial security; he put more time into the teaching of calculus. Just as Johann had been indifferent to the idea of becoming a businessman like his father had wanted and instead went into medicine; so did Daniel follow the duplicate path. While in school for his doctorate, Daniel looked over the theories dealing with kinetic energy.

Daniel’s doctorate dissertation on the function of respiration and the mechanics involved. This involved the physics involved with breathing, so math came into play towards his doctor certification. By the time 1720 came, Daniel would have earned his medical doctorate.

Although young Bernoulli had the status now to put up a shingle and practice as a physician; he sought to perform in an academic status if possible. Daniel tied to apply to fill various heads of departments in different disciples at the University of Basil. However, would not play to his favor and was denied all the positions he put in for simply because the lots that were drawn did not go on his side.

Instead of being discouraged, Daniel continued to study and learn all he could about math, calculus, physics and corresponding disciplines. After a couple of years, he left Switzerland and moved to Italy in 1723. Although he moved there with the intent of studying medicine; Bernoulli found himself becoming immersed he began looking at the works of Galileo and how to apply mathematics to the larger question of the universe.

Much of his time was spent in Venice as His health precluded him from travelling to other areas of Italy to learn more about medicine. With the aid of a Prussian mathematician, his first publication was created entitled, *Mathematical Exercises. *One aspect of the work dealt with pressure as illustrated by water flowing from a container opening. His interest in the area of pressure was making headway based upon the information from the publication. Another area had to do with a geometry problem. Finally, another aspect of the work detailed issues of probability. The book was basically random looks at various mathematical topics.

In 1725, Daniel Bernoulli returned to Basel from having been in Italy for over two years. Once there he learned that he had received an honor from the Paris Academy. He had developed a naval instrument dealing with time. He perfected an hourglass to handle the briskest of weather related wave rolls which he submitted to the Paris Academy.

His publication he had printed in Venice was so well-received that was offered at position of the mathematics department in St Petersburg’s University. His older brother Nicolaus would join him in St. Petersburg as he too was offered a position. Unfortunately, within a year of taking up residence there, the older Bernoulli would succumb to illness and pass away. This tragedy, plus that of his own poor health in the extreme cold of St. Petersburg made Daniel miss the climate he enjoyed back in Switzerland.

However, Daniel Bernoulli would remain in St. Petersburg for a number of years; which turned out to be a good thing in regards to his learning and accomplishments. During these years he would lecture extensively about his many passions; including physics and medicine. His father had sent Daniel a helper in that of man named Leonard Euler. Euler had been one of Johann Bernoulli’s top students at university.

One of the things that Euler’s presence brought to that of Bernoulli, besides a face from home, is someone to bring accountability and a second “mind’s eyes” to the work that they would be studying together. The area of rotation and vibration in bodies was one of the areas of study that the two men would be involved in. It should be noted that in time, Leonard Euler would also become a renowned name in the world of mathematics.

Harmonic vibrations are one area that caught Bernoulli’s attention. He learned that stringed instruments represented a perfect example of this quality. His work with harmonic vibrations placed upon the strings of violins for example, developed oscillations. The two men also did a study on probability economy. This work stepped a bit into philosophy in that the money someone makes has an effect upon their moral disposition.

During the remainder of his time in St. Petersburg, (even with Euler present, Daniel Bernoulli still dislikes the climate and memory of his brother’s death that the city holds) Bernoulli puts more attention on the study of Hydrodynamics. The word represents the factors involved with the flow of fluid (fluid flow) by understanding density of fluid, the velocity in its motion and the pressure involved within the flow. It is from this study that perhaps his most famous discovery comes with his name, Bernoulli Principle, in which as fluid velocity gets higher the pressure behind the flow becomes lower.

During this time Bernoulli also puts work into what is called “kinetic theory of gases” along with heat. This discussion was around the idea of how molecule movement on a surface would occur and would affect pressure and motion as temperatures increased.

This discussion would be published in his next publication, *Hydrodynamica *that came out in 1738. Bernoulli leaves St Petersburg in approximately 1734; along with that of his brother Johann II, who had moved to St Petersburg sometime prior. Since he had left about four years before its publication, it appears that the printer had delayed the book’s publication by four years for some unknown reason.

The book also discusses the nature of pumps to be able to lift water and move it along. The contents of the work added immensely to the reputation of Daniel Bernoulli. Some say that the reason his father Johann wrote a book similar to Daniel’s work was out of nothing but jealousy.

When Daniel does leave St Petersburg to move back to Basel; he and his younger brother spend some time travelling through Europe. They decide to spend time seeing the continent and bonding before taking on his new position as a professor in botany. It may not have been his first choice for academia as he had a passion to teach in the mathematics area, but it was a far cry better than remaining in St. Petersburg in his belief.

An opinion exists as to the friction of Daniel with his father Johann Bernoulli. His father had always prided himself as being somewhat better than Daniel in the areas of mathematics. In 1734, both men receive mutual honor in an entry to the Paris Academy. (This is the same Academy Daniel had earlier received a gold medal for his work with the naval hourglass.) This apparently did not set well with the elder Bernoulli as he was not willing to be accepting of his son’s success equaling his own. This meant that Johann’s pride got in the way and caused an estrangement between both Bernoullis. Although Daniel now lived in Basel again; Johann wanted no further contact.

Johann went a step further by publishing a work, *Hydraulica, *which had extensive similarities to Daniel’s book. Published a year later than that of Daniel’s work, Johann schemed to make his book seem to be an earlier production by 6 years. His pride was on the line and he apparently no intention of allowing his middle son have a greater legacy than his own. One positive not is that the youngest Bernoulli, Johann II, favored his brother and later would team with him to publish a work together.

In 1737, Daniel Bernoulli won top prize at the Paris Academy. This time his prize was based upon the idea for a best in design shape for an anchor.

Daniel Bernoulli never forgot his companion and associate Leonard Euler. He stayed in communication with Euler and the two worked on ideas together. Euler had the unique ability of creating the mathematics that represented Bernoulli’s concepts. An example of this is found in their collaboration with vibrations. Their work would be included in the 1738 book publication by Bernoulli with their study of ship propulsion.

In 1743, Daniel Bernoulli was able to transfer from department of botany to that of physiology. This represented his familiarity with the medical field and was a bit closer to his heart. He continued teaching in this arena for seven years when he finally was made head of the physics department. Daniel Bernoulli had a love for physics of math and especially for that of Sir Isaac Newton. The conflict of calculus that Newton and Liebniz was a constant division among mathematicians. However, Bernoulli tended to side with that of Newton. Newton’s concepts were used by Bernoulli in the physics of motion.

**Accomplishments**

Bernoulli was a man of wide experience and study. Because of this he was a man that was able and willing to study many areas of interest that involved physics and other math disciplines. He would continue to enter for prizes at the Paris Academy and have a legacy of success. Some of these included his work with Euler in understanding tides in 1740. He gained recognition and prizes in for his work with magnetism. In 1747 a nautical prize again for determining how long time at sea was measured. Similarly, in 1751 for understanding the currents of the ocean. In all, Daniel Bernoulli would win notoriety 10 times from the Paris Academy.

Daniel Bernoulli passed away in 1782. It is not clear if he ever made amends with his father over his successes. It can be said that Bernoulli never sought to have the conflict and the onus was on that of his father, Johann Bernoulli.

Daniel Bernoulli lived a long life considered for the time of 82 years. One thing that can be said about the man is he loved his work and devoted himself tirelessly to its pursuit.