In his early years Brasseur was self-educated but even this presented difficulties since a lack of money meant he could only have a few books from which to study. After being given a little private tuition, he entered the Athénée of Luxembourg which prepared him for university studies. He was, of course, not the only young man to suffer difficulties in hard times so he was one of a large group of young people at the Athénée who were passionate about the opportunity to study. Already he had developed a love for science so, when he entered the University of Liège in 1824 at the age of 22, he matriculated in the Faculty of Science. There he studied metaphysics with Bernard-Ignace Denzinger, who held the chair of philosophy at the University of Liège. He studied mathematics with Richard van Rees (1797-1875), Jean-Michel Vanderheyde (1767-1836) and Germinal Dandelin (1794-1847), and he studied science with Jean-Charles Delvaux de Fenffe (1782-1863). It was Dandelin who had a profound influence on Brasseur - he taught him geometry and encouraged him to undertake research on that topic. Brasseur was awarded his doctorate in mathematics and physics in 1829 for his thesis De resolubilitate functionum algebricarum integrarum in factores primi vel secundi gradus . He then went to Paris where he spent a year attending mathematics lectures at the Collège de France delivered by Jacques Binet and at the Sorbonne by Jean Hachette and by Augustin-Louis Cauchy. He also attended lectures at the Sorbonne by the chemist Louis-Jacques Thénard (1777-1857), by the physicists Jean-Baptiste Biot (1774-1862) and Claude Servais Mathias Pouillet (1791-1868), and by two scientists who researched in both physics and chemistry Joseph-Louis Gay-Lussac (1778-1850) and Pierre Louis Dulong (1785-1838). However, there was a revolution in Paris in July 1830, and it was following this that Brasseur left the city and returned to Liège.
At this time Brasseur began twin careers, one as an academic and the other in the military. He began teaching mathematics in a private capacity and was also a captain in the artillery of the Civic Guard of Liège. Now we have to look briefly at the events of the time to understand the events of Brasseur's life. We have already noted the effects of the Napoleonic wars on Brasseur's education. After the defeat of Napoleon, the Allied powers did not want Belgium to remain under French control so in 1815 they created the Kingdom of the Netherlands from Belgium and Holland with William I as King. The north and south, which had been united until the 16th century, had developed very differently during their centuries apart. William began a process of increased industrialisation in the south, building roads and bridges, and also set up two new state-funded but partially autonomous universities at Ghent and Liège, the latter being where Brasseur studied. However, following the Paris revolution of 1830, there was a movement, particularly strong in Liège, for an independent Belgium. Both sides prepared for war but an international conference in 1831 recognised Belgium as an independent country.
Brasseur began giving courses on analytic geometry and descriptive geometry which were designed to complete the instruction of lieutenants of artillery and so allow them take the examinations of the École Militaire necessary to rise to the rank of captain. In 1831 he was appointed to a project constructing roads and bridges in the Brabant region of Belgium. In the same year, on 1 September, he married Thérèse Grosfils, who came from Liège. He was assigned to oversee naval work at Boom but, as the work was still at the planning stage, he was sent to Louvain to await developments. The university at Louvain was an ancient one, founded in 1425, but it had been suppressed at the time of the French Revolution in 1797. A temporary Faculty was in its place when Brasseur arrived there and he taught elementary mathematics in that Faculty until 1832. In fact the university would be re-established two years later but by this time Brasseur held a position in Liège. He had for a long time wanted an academic position and in 1832 he was appointed as a lecturer at the University of Liège to teach the course on Descriptive Geometry and also the course on Higher Analysis Applied to Geometry. He based his geometry courses on the work of Gaspard Monge.
Now we noted above that William I set up the University of Liège following the creation of the Kingdom of the Netherlands in 1815. This had happened in 1817, but in 1831 Belgium had become independent and, as a consequence, the university was reorganised and it became a fully state run university in 1835. At this time Brasseur took over teaching the Analysis course, the Elementary Mathematics course, and was appointed to the Chair of Applied Mechanics and the Chair of Descriptive Geometry. Two years later he became an extraordinary professor and, in the same year, published his book Programme du cours de géométrie descriptive donné par J-B Brasseur . This text was very well received with a second edition appearing in 1850, a third in 1860 and a fourth edition in 1867. When the Royal Society of Sciences of Liège was set up in the 1830s, Brasseur, who was a founder member, was appointed as its first Secretary General, serving in that capacity under four presidents. He was elected to serve as president of the Society in January 1849. By this time he had been promoted to full professor, which happened in 1844.
Brasseur's publications, following those mentioned above, include: Applications des projections cotées à diverses recherches sur l'étendue (1841); Lignes de courbure de quelques surfaces exprimées par des équations différentielles partielles, et note sur une propriété de l'hyperboloïde à une nappe, et du paraboloïde hyperbolique (1843); Sur la double génération des surfaces du second degré par le mouvement d'un cercle (1843); Note sur un nouvel énoncé des conditions d'équilibre d'un système de forces (1846); Mémoire sur divers lieux géométriques du second degré, déterminés par la géométrie descriptive (1846); Transformation du principe des moments en celui des vitesses virtuelles et note sur une construction géométrique de la surface d'élasticités (1849); and Note sur une construction graphique de centre de gravité d'un polygone quelquonque, en supposant connue la construction du centre de gravité du triangle (1849). Perhaps his most significant geometrical contribution, however, was his 148-page memoir Sur une nouvelle méthode d'application de la géométrie descriptive à la recherche des propriétés de l'étendue which he published in the Memoirs of the Royal Belgium Academy of Science in 1855. The memoir contains an original presentation of projective geometry.
Jean-Baptiste and Thérèse Brasseur had five children. Their daughter, Constance (1836-1912), married Dominique Brasseur (1833-1906), one of sons of Jean-Baptiste Brasseur's father Alexis with his second wife Marie-Anne Schockmel. Jean-Baptiste and Thérèse Brasseur had a four sons, Paul, Alfred, Auguste and Leopold. Alfred (born 1835 in Liège, died 1898 Brussels) made a career in the army and was an inspector of studies at the École Militaire. Leopold followed his father in becoming a mathematician, becoming a lecturer in Liège in 1858. He took over some of his father's courses and published the paper Démonstration d'un théorème de Steiner in 1865 but, sadly, died in the year this paper was published. Brasseur died three years after Leopold's death following a chill. Following his death, François Folie edited two of Brasseur's works, namely Précis du cours de mécanique appliquée and Exposition nouvelle des principes du calcul différentiel et intégral which were both published in 1868.
We have already noted above the honour that was given to Brasseur by his election as president of the Royal Society of Sciences of Liège. He was also honoured by being elected a corresponding member of the Royal Belgium Academy of Science on 17 December 1847 and a full member of the Academy on 14 December 1855. He was elected as a corresponding member of the Society of Natural Sciences of Luxembourg on 15 June 1864. On 26 October1860, Brasseur received the Knight's Cross of the Order of Leopold. The Knight's Cross is the highest of five classes of the Order of Leopold which is the highest order of Belgium named in honour of King Leopold I. On 19 February 1868 Brasseur was appointed Officer of the Order of the Oak Crown by the king of the Netherlands and the Grand Duke of Luxembourg. The Officer is the second highest of five classes of the Order of the Oak Crown, instituted by the Grand Duke King William II in 1841 when he ruled over both the Grand Duchy of Luxembourg and the Kingdom of the Netherlands.
Lucien Godeaux sums up Brasseur's achievements in :-
Brasseur's biographers agree in their praise of the clarity and precision of his teaching, and these qualities are reflected in his works and in his memoirs. He has had a profound influence on mathematics education at the University of Liège and was the founder of the School of Geometry that continued to shine brightly with his successors F Folie, C Le Paige and Fr Deruyter. On the other hand, he had the idea to create a laboratory for applied mechanics; it was the latter that later supported V Dwelshauvers-Dery's research on the steam engine.His energy was nicely illustrated by his son Alfred Brasseur who said (see ):-
Never in his life did Brasseur sit in an armchair.
Article by: J J O'Connor and E F Robertson