Wednesday, October 22, 2014

The Planetary Tables of Erasmus Reinhold

On October 22, 1511, German astronomer and mathematician Erasmus Reinhold was born. He is considered to be the most influential astronomical pedagogue of his generation. Furthermore, he is best known for his carefully calculated first set of planetary tables applying Copernican theory, published in 1551.

Erasmus Reinhold was born and died in Saalfeld, Thuringia, Germany. His father Johannes Reinhold was a tax collector. In 1530 went to Wittenberg to study at the Academia Leucorea under Jacob Milich, from where he graduated in 1535 as Magister. In 1536 he was appointed professor of higher mathematics by Philipp Melanchthon. In contrast to the limited modern definition, "mathematics" at the time also included applied mathematics, especially astronomy.

His colleague, Georg Joachim Rheticus, also studied at Wittenberg and was appointed professor of lower mathematics in 1536. Reinhold catalogued a large number of stars. In summer 1549 he became dean of the artistic faculty and one year later principal of the university Wittenberg. His publications on astronomy include a commentary on Georg Purbach's Theoricae novae planetarum. Reinhold knew about Nicolaus Copernicus and his heliocentric ideas prior to the publication of De revolutionibis and made a favourable reference to him in his commentary on Purbach.

However, Reinhold like other astronomers translated Copernicus' mathematical methods back into a geocentric system, rejecting heliocentric cosmology on physical and theological grounds. In 1551, Duke Albert of Brandenburg Prussia supported Reinhold and financed the printing of Reinhold's Prutenicae Tabulae or Prussian Tables, upon which Reinhold spent seven years labour. These astronomical tables helped to disseminate calculation methods of Copernicus throughout the Empire. Both Reinholds's Prutenic Tables and Copernicus' studies were the foundation for the Calendar Reform by Pope Gregory XIII in 1582. With his tables, Reinhold intended to replace the Alfonsine Tables; he added redundant tables to his new tables so that compilers of almanacs familiar with the older Alfonsine Tables could perform all the steps in an analogous manner. Copernicus's heliocentric claims did not, then, win over the hearts of all European astronomers overnight. Rather, the Prussian Tables became popular in German speaking countries for nationalistic and confessional reasons, it seems, and it is through these tables that Copernicus's reputation was established as a skilled mathematician or an astronomer on a par with Ptolemy, and helped to disseminate the Copernicus' methods of calculating the positions of astronomical objects throughout the Holy Roman Empire.

Erasmus Reinhold died in 1553 in Saalfeld because of a lung disease at age 42.

At yovisto, you can learn more about the scientific, social and religious impact of the Copernican Revolution with the lecture 'Mathematics, Motion, and Truth: The Earth goes round the Sun' by Jeremy Gray of Gresham University.



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Tuesday, October 21, 2014

Samuel W. Alderson and the Crash Test Dummies

Thy Hybrid III crash test dummy family
On October 21, 1914, US-american engineer Samuel W. Alderson was born. He is best known for his development of the crash test dummy, a device that, during the last half of the twentieth century, was widely used by automobile manufacturers to test the reliability of automobile seat belts and other safety protocols.

Samuel W. Alderson attended several colleges including Reed College, California Institute of Technology, and the University of California Berkeley. However, his higher education was interrupted by his periods of working at his family's sheet-metal business. Alderson started his PhD in physics at the University of Berkeley under J. Robert Oppenheimer and E.O. Lawrence, but never finished his dissertation. He began developing electric motors for missile guidance systems during World War II and continued his career at IBM in order to design motor-powered prosthetic arms. Alderson founded his own company in 1952 in order to create anthropometric dummies to test the safety of the ejection seats used in aircraft.

Back then, the automobile industry became also increasingly interested in testing the impact of strong forces to the human bodies like in car accidents. It is known that the first experiments were performed with cadavers, mostly older white male bodies were used. Then, volunteers served as living crash test dummies before living animals (mostly pigs) were used to collect the data. However, tests like these were highly controversial. Also, it was hard to collect reliable data that was comparable, since cadavers differed from each other and often could only be used once. Thus, Alderson began creating an anthropometric test dummy that could be mass-produced, tested, and re-tested. [2]

Other companies enteres the market as well. The very first test dummy was called 'Sierra Sam' followed by Alderson's V.I.P produced in 1968. The V.I.P had a steel rib cage, articulated joints and a flexible neck, with cavities to hold instrumentation, and was designed to mimic the acceleration and weight distribution properties of an average male. The Hybrid I was introduced in the 1970s by General Motors, which combined Alderson's design with that of Sierra Engineering. The following most notable versions were titled Hybrid II and III and had improved neck flexibility and head rotation. Also, the bodies not only simulated a male body anymore, whole dummy families have been created to improve safety in automobiles.

In the further development of crash test dummies, models were designed for specific impacts, like front or side crashes. Side impact dummies would measure, what happened to the ribs, the spine and internal organs. To the most advanced dummies belong WorldSID model, able to record 258 separate measurements in one test, and the prototype from Denton ATD, with LEDs on each of the dummy’s 12 ribs that can then be tracked by light-angle sensors, thereby measuring movement in all three dimensions.

Samuel Alderson also became known for his humanoid figures that were able to dub medical phantoms. They were designed to measure radiation exposure, as well as synthetic wounds worn by soldiers during training exercises. The dummies were even capable of oozing fake blood. However, his contribution to automotive safety, in the form of the crash test dummy, that saved the most lives and become an icon of popular culture.

At yovisto, you may be interested in crash test dummy footage.



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Monday, October 20, 2014

Vannoccio Biringuccio and the Art of Metalworking

De la Pirotechnia (1540)
by Vannoccio Biringuccio
Probably on October 20, 1480, Italian matallurgist Vannoccio Biringuccio was born. He is best known for his manual on metalworking, De la pirotechnia, published posthumously in 1540. Biringuccio is considered by some as the father of the foundry industry.

Biringuccio was born in Siena to Paolo Biringuccio, thought to have been an architect and public servant, and his mother was Lucrezia di Bartolommeo Biringuccio. He was baptised on October 20, 1480. Thus, he might have been born the day before. He was a follower of Pandolfo Petrucci, the head of the powerful Petrucci family, the rulers of the Italian city of Siena. As a young man Biringuccio was travelling in Italy as well as in Germany inspecting metallurgical operations. After running an iron mine and forge at Boccheggiano for Pandolfo Petrucci, he was appointed to a post with the arsenal at Siena and in 1513 directed the mint. When Pandolfo died, Biringuccio remained tied to the Petrucci family, being employed by Pandolfo's son Borghese Petrucci. However, the uprising of 1515 forced Borghese to flee from Siena, taking Biringuccio with him. Biringuccio traveled about Italy, and visited Sicily in 1517.

In 1523 Pope Clement VII caused the reinstatement of the Petrucci family, and along with them Biringuccio was able to return from exile. In 1524 he was granted a monopoly on the production of saltpeter across all of Siena. However, this was short lived — already in 1526, the people of Siena revolted and threw the Petrucci family out again. Although, the family made an attempt aided by Biringuccio to regain Siena by force, but it failed. Thereafter Biringuccio served the Venetian and Florentine republics, and cast cannon and built fortifications for the Este and Farnese families.

In 1530, Siena entered a more peaceful phase, and Biringuccio returned, time in honor, as senator and, succeeding Baldassare Peruzzi, as architect and director of building construction at the Duomo. In 1538 he became head of the papal foundry in Rome, and director of munitions. His exact place and date of death is unknown; all that is known is that a document dated 1539 mentions his death.

The reason for Biringuccio's fame is certainly the publication of his manual on metalworking, De la pirotechnia, published posthumously in 1540. Thus, Biringuccio is considered by some as the father of the foundry industry as De la pirotechnia is the first printed account of proper foundry practice. It also gives details of mining practice, the extraction and refining of numerous metals, alloys such as brass, and compounds used in foundries and explosives. It preceded the printing of De re metallica by Georg Agricola by more than a decade. Moreover, Agricola's famed sections on glass, steel, and the purification of salts by crystallization are in fact taken nearly verbatim from the Pirotechnia. The work is one of earliest technical manuscripts to survive from the Renaissance, and is thus a valuable source of information on technical practice at the time of writing. The work was printed in 1540 in Venice, and has been reprinted numerous times [2].

Biringuccio is also important in art history for his description of the peculiarly Renaissance arts of casting medallions, statues, statuettes, and bells. His account of typecasting, given in considerable detail, is the earliest known. The Pirotechnia contains eighty-three woodcuts, the most useful being those depicting furnaces for distillation, bellows mechanisms, and devices for boring cannon and drawing wire.[2]

A member of Fraternita di Santa Barbara guild, before his book information on metallurgy and military arts were closely held secrets. In fact, his book is credited with starting the tradition of scientific and technical literature.[2] Also, Pirotechnia offers one of the first written attempts to explain what causes a rocket to move. Biringuccio attributed the propulsive force to a "strong wind":
One part of fire takes up as much space as ten parts of air, and one part of air takes up the space of ten parts of water, and one part of water as much as ten parts of earth. Now sulfur is earth, consisting of the four elementary principles, and when the sulfur conducts the fire into the driest part of the powder, fire, and air increase ... the other elements also gird themselves for battle with each other and the rage of battle is changed by their heat and moisture into a strong wind. (Vannoccio Biringuccio, De la Pirotechnia, 1540)
At yovisto, you can learn more about the epoch of the European Renaissance in the lecture of Prof. Thomas W. Laqceur from Berkeley on 'European Civilization from the Renaissance to the Present'.



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