Giovanni Battista Venturi

Italy (1746-1822)

Giovanni Battista Venturi is an Italian scientist born in 1746. Venturi was "fascinated by the history of science as [..  well as] by its application," and was "one of the first to call attention to Leonardo Da Vinci's ‘work as a scientist and engineer" (2). He was also the first to note the effects of constricted channels on fluid flow (1).

Giovanni Venturi's primary expertise was in fluid dynamics and hydraulic engineering. He built on “the work performed by David Bernoulli and Leonard Euler”(2). Venturi discovered that when fluid goes into a constricted area of a pipe, the fluid’s velocity increases and its static pressure decreases. If the velocity stayed constant, rather than increasing, then weird things would happen to the matter present in the pipe, breaking the law of the conservation of matter. Meanwhile, if the pressure stayed constant, rather than decreasing, then the kinetic energy produced by the velocity would not follow the law of conservation of energy, again causing physics problems.

By 1769, 23-year-old Giovanni Venturi was ordained and became a professor. In 1774, he was appointed as professor of geometry and philosophy at the University of Modena. (2) In 1778, he was promoted to Professor of experimental physics. During his tenure, he was also the state engineer and state auditor for the Duke of Modena, as well as ducal mathematician. He “served in many diplomatic appointments on France & Switzerland” and met with fellow scientists there. He retired in 1813, “but continued to publish his own works and compile works of other famous scientists until his death in 1822.” (2)

The Venturi effect is something we use to this day. For example, a Venturi nozzle can generate a velocity high enough and a pressure low enough to draw a vacuum.

[Edited June 30 2022 for clarity]

Works Referenced

(1) Bernoulli's Theorem https://www.britannica.com/science/Bernoullis-theorem#ref254081

(2) Venturi Effect  http://glewengineering.com/italian-masters-venturi-and-the-venturi-effect/amp/

Roger Bacon

England 1214-1294

Roger Bacon, also known as the Doctor Mirabilis, or Wonderful Doctor, was born in Ilchester, Somersetshire, England in the early 13th century into a wealthy family, and was exposed to geometry, music, astronomy, the literary classics of the 13th century, and arithmetic early on. (1) When he was older, he pursued higher education at Oxford and in Paris, joined the Franciscans, and went on to work at Oxford, a school run by the Franciscan order.(2)

Beginning in 1247, Bacon devoted significant periods of time to experimental science. According to the Jacques Maritain Center, “he was the most important cultivator of the natural sciences who appeared during the Middle Ages.” (3) He was suspicious of rational deduction, preferring to “confirm experiences.” He carried out several in-depth experiments on light and rainbows, as well as several thought experiments on other topics. (1)

For some years, starting in 1260, the Franciscan Order prohibited its members to publish works outside of the order unless the work went through a detailed process, as a way to prevent the spread of heresy. The order was still fairly young, and it made sense to try to fix these problems internally. By 1266, however, the rule around publishing works had changed, which allowed Bacon to publish his books for the general educated public. (2)

Bacon wrote several works, but the most famous are his “Opus Majus” and the “Compendium philosophiae”. He was a philosopher, and within the Opus Majus he wrote at length about “the relation between theology and philosophy, ... that all science are founded on the sacred sciences, especially on Holy Scripture, [and on] the necessity of studying zealously the Biblical languages, as without them it is impossible to bring out the treasure hidden in Holy Writ.” (2)

The Compendium contained “an important section on his theory of language and translation” which included Bacon's belief that “name and signification are imposed on the present object, and these are opened to past and present on the basis of verbal tense.” Theoretically, this would result in less ambiguity in conversation, or at least less ambiguity if people pay strict and careful attention to how they phrase things. (4)

He also studied optics and alchemy, and was the first European to describe the process of making gunpowder (1). Bacon was the first European to propose the idea of flying machines, although he envisioned flying machines which relied on flapping mechanisms, not the stiff wings used in modern airplanes. This, one might argue, is because the scientists in those time periods had to rely on what observation they could capture at the speed of the human eye, and what those observations indicated was that birds flapped their wings to move forward and to stay up in the air. The observations didn’t capture the thermals (practically invisible to the human eye) that birds of prey used to make flight easier, and they didn’t capture the way that some birds shift between soaring on extended wings and flapping their wings to keep moving.

Bacon also proposed the idea of motorized ships and carriages, which is especially interesting when one considers that the electric motor was not invented until five and a half centuries later in 1760. This meant that Bacon was basing his ideas of motorized carriages and boats off of the types of motors used for watermills and windmills.

Roger Bacon is an excellent example of a man who worked on both the science of this world, experimental science, and the science that deals with the next world, theology. His extensive work in such wide-ranging fields truly earns him the title “Wonderful Doctor”

Works Referenced

1. Roger Bacon: English Philosopher and Scientist https://www.britannica.com/biography/Roger-Bacon
2. Roger Bacon http://www.newadvent.org/cathen/13111b.htm
3. The Experimental Sciences -- Albertus Magnus -- Roger Bacon https://maritain.nd.edu/jmc/etext/staamp3.htm
4. Roger Bacon https://plato.stanford.edu/entries/roger-bacon/

Albertus Magnus

Germany 1200-1280

Albert Magnus is perhaps the foremost example of a religious scientist. He explored so many topics he had no specific area of focus, writing on such diverse topics as rhetoric, math and logic to astronomy, theology, and politics.

 In short, however Albert’s work is best summarized by saying he wanted to explain everything. He did not have a specific discipline but worked to bring together all the knowledge of the time together. His aim was to explain the various scientific disciplines to be widely understood (Encyclopedia Britannica 2018). Many of his works were based on Aristotle, but when that was lacking, he created his own work, and even when basing his information off that of Aristotle, he was always making something new, shifting ideas and reformulating them to be more easily understood.

Albert was the preeminent natural scientist of his age, using faith and reason together. The truth could not be in conflict with itself, as it would be if faith and reason were mutually exclusive. Rather, ordinarily everything is explainable by both, though a few things may require faith. He created commentaries on a plethora of works, notably the Bible and the foremost theological textbook of the time, Peter Lombard’s Sentences, as well as examining and commentating on all the available works of Aristotle (Encyclopedia Britannica 2018). There were severe issues involved given the breadth of Aristotle’s work and the fact copies were often lacking, so Albert made do with what he could (The Book of Minerals). Simply commenting on Aristotle’s work was quite an undertaking as the subjects ranged from Physics, and Meteorology, to The Soul, Life and Death, and the Movement of Animals. Albert spent a great deal of time honing the specific ordering, starting with Physics and finally rounding out the collection of work with Animals. That being said, his collection of works under Natural Sciences also include entries not backed by actual Aristotelian works. Interestingly, Albert was quite ready to create a new piece of work if there was an apparent gap, thus such titles as The Book of Minerals, which covered the subject of geology and why different gemstones have differing properties (The Book of Minerals). Albert was unable to locate the ancient text, but since he was already ‘rewriting’ them, after a fashion, he delved into the subject.

While the science appears quite incomplete to the modern eye, at the time, science was a much more philosophical undertaking. Instead of numbers and measurements ruling everything, the qualitative data, the purpose of things was attempted to be understood. For example, when attempting to approach metals and gems, the question was what are the essential properties that make up that thing, and what are the accidental properties. Essential properties are the qualities that have to be present for the thing to be classified as what it is, while accidental properties are variable depending on the subject, like a person’s eye color. (The Book of Minerals xxxiii). At the time, of course, the kind of science we know today was not present, but science was more akin to philosophy, perhaps something somewhat akin to theoretical physics today.

Despite his fame, much of the information about Albert Magnus’s life is uncertain. He was born in Swabia, Germany in a noble family, around about 1200 AD, plus or minus about six years. (1) The nobility of his family, actual date of birth, and a myriad of other details, such as essentially his entire childhood, are extremely uncertain, likely due to his fame. (1)

The first sure detail is that he joined the Dominican order, though again the date is an issue. According to the Encyclopedia Britannica it was in 1223, but an expert who translated one of Albert’s books on geology found it more likely the date was 1226.
By 1245, his life was well underway, as his star pupil Thomas Aquinas arrived in Paris

Albert joined the Dominican order in 1223, and by 1245 had gone to Paris to study at the Dominican convent of Saint-Jacques. While at Saint-Jacques he commenced his teaching career, lecturing on the Bible and Sentences, the main theological textbook of the time, for two years apiece (Encyclopedia Britannica 2018). Even during his life, he was recognized as a great authority on various topics, and was sent to Cologne to advance learning by establishing the first Dominican ‘general studies’ school (Encyclopedia Britannica 2018). While acting as head of the school, he wrote and taught as he wished.

However, from 1254 to 1264 he had other duties. In 1254 he was made head of the German section of the Dominicans, holding the office for three years, still maintaining his writing and research. He decided to resign in 1257 so he could return to Cologne and then the Pope, Alexander the IV, appointed him Bishop of Regensburg. With the death of the Pope in 1261, Albert resigned his office, but was once again called by the Pope to serve Christendom. For 1263 and 1264 he assisted Urban IV by rallying support for the Crusades in Germany. After lecturing at a couple of other cities, he finally returned to Cologne. (Encyclopedia Britannica 2018)

Of course, even this did not last. In 1274, he was off to the second Council of Lyons. Once there, he assisted in choosing the German monarch (Encyclopedia Britannica 2018). Then a few years later, in 1277, he journeyed to Paris to Albert uphold Thomas Aquinas’ reputation and to explain their position on various points of Aristotle that were held in question (Encyclopedia Britannica 2018).


Albert Magnus’ extensive writing and enormous influence extends far beyond his own time, all the way to the present day, with such fervor as to be almost impossible to categorize. His work extended as far as the time would allow, most notably in the natural sciences perhaps, but astounding in every field. Not only was he a dedicated researcher, he was a prolific writer dedicated to explaining Aristotle’s thought processes and the world as a whole in simple enough terms for all to understand.


Works Referenced

1. St. Albertus Magnus https://www.britannica.com/biography/Saint-Albertus-Magnus
2. Albert Magnus: The Book of Minerals https://archive.org/details/308059821ALBERTUSMAGNUSTheBookOfMinerals 

Further Reading

• The Mediaeval Mind: A History of the Development of Thought and Emotion in the Middle Ages - Vol. 2 https://www.questia.com/read/9357714/the-mediaeval-mind-a-history-of-the-development-of 
• Great Dominicans: Albertus Magnus https://www.english.op.org/godzdogz/great-dominicans-albertus-magnus 
• Albert the Great https://plato.stanford.edu/entries/albert-great/ 

Bernard Bolzano

Bohemia (Now roughly the Czech Republic ) 1781-1848

Bernard Bolzano was many things, though principally a philosopher and mathematician. He was born in Bohemia, now the Czech Republic, and spoke and wrote German. He studied mathematics and philosophy at the Charles-Ferdinand University of Prague. Starting in 1800, he studied theology and graduated in 1804 (2). At this point, he had two positions open to him, as a professor of mathematics or a position in science and religion (2). Bolzano chose the science and religion route and was ordained in 1805, achieved his doctorate in philosophy and started working. 

However, he got into trouble because of his desire to reform the Austrian Empire. He thought war, and militarism in general, was terrible unnecessary and led a movement to refocus Austria on peace. (3, 4). At the time, most of Austrian society was built around the military and Bolzano wanted Austria's education and society to consider peace instead (3). He created a book on the subject, entitled On the Best State in which he imagined a government dedicated to reducing human suffering and misery as effectively as possible.  (1). 

As Napoleon was still attempting to conquer Europe at the time, Bolzano's views were taken none too well, and he was investigated for heresy. In 1819 he was drummed out of the university and banned from publication (3). He was eventually able to around the ban by getting some of his contacts and students to publish some of his work (1).

Bolzano achieved a level of insight into a variety of fields, mostly on a logical, mathematical, and philosophical basis. He tended towards existential issues, trying to establish concrete reasoning to get to the heart of the matter. Bolzano wrote in such diverse fields as the aesthetic, the theological, the logical, and the mathematical (1).

Bolzano wrote on the subject of art and beauty, and attempted to scientifically describe beauty. He was not actually successful. He argued that objects were beautiful if they "can give to all human beings properly developed in their cognitive faculties a pleasure, and the reason for this is that... [it] gives them at least an obscure intuition of the proficiency of their cognitive faculties" (1). As with some of his other philosophical work, it gives a definition, that leaves a lot to be desired. For instance, what does ‘proper development’ for cognitive faculties look like? Rather than being objective, his definition ends up being extremely subjective.

As for theology, he wanted a rational and credible lens through which to interpret miracles so he wrote extensively on probability theory in his theological works, trying to establish how to ensure the event had was improbable, that is less than 50% chance of occurring. He was not extremely concerned with the exact probability beyond that, just how to make sure it was sufficiently improbable to be considered a miracle (1). 

As for logic, Bolzano imagined three 'Worlds.' The first contains all material things, the second for psychological (and presumably emotional) ideas, and the third only for logical ideas and concepts. Then, he wanted to prove, without assumptions, that true statements existed (1). He created a proof to demonstrate there must exist an infinite  number of true statements existed. His proof flowed in a logical, almost mathematical way. 

Firstly, he examined the statement that there were no true statements, in and of themselves. Then, he examined the preposition that there are no true statements, found that must itself be a preposition and therefore proving at least one preposition, or statement not based on assumption exists. From there, he continued by plugging in the first result again. If there is one true statement, the statement that there is only one true statement means there is at least one MORE true statement and so on. Hence, an infinite number of true statements exist (1).

Among Bolzano's mathematical feats were creating a better proof for the bionomial theorem, applying probability to limits, and creating the Bolzano-Weierstrauss Principle (3, 5, 6). Of all his work, his mathematical contributions have been the most important. 

Works Referenced

1. Bernard Bolzano https://plato.stanford.edu/entries/bolzano/
2. Bernard Bolzano: Philosophy of Mathematical Knowledge http://www.iep.utm.edu/bol-math/
3. Bernhard Bolzano https://www.britannica.com/biography/Bernhard-Bolzano
4. Selected Writings on Ethics and Politics https://brill.com/view/title/30750
5. The Philosophy of Bernard Bolzano: Logic and Ontology https://www.ontology.co/bolzanob.htm 
6. The Bolzano-Weierstrauss Property and Compactness http://www.u.arizona.edu/~mwalker/econ519/Econ519LectureNotes/Bolzano-Weierstrass.pdf