Blessed Francesco Faà di Bruno

This Italian priest, mathematician, and musician (1825—1888) began his career as a staff officer in the Royal Army of Sardinia and participated in the First Italian War of Independence. While in combat, Faà di Bruno’s horse was killed by Austrian rifle fire, so he mounted another horse only to have that killed too. After being wounded in the leg, and seeing his friends killed, he resigned his commission in order to begin a doctorate in mathematics. He had the good fortune to study under two devout Catholics, Augustin Cauchy and Urbain Le Verrier, both already famous for their joint discovery of Neptune. While in Paris, he joined the Saint Vincent de Paul Society (1850) with Cauchy and Adolphe Baudon, and later established a chapter in Turin (1853). While in Paris he invented a mechanical device to allow blind people to write, in no small part because his sister Maria Luigia was becoming blind. He would eventually go on to invent a differential barometer, described in a publication of 1870, and an electric alarm clock.

On his return to Turin, he was appointed a math professor at the university, where he soon befriended St. John Bosco and joined the work to help the poor. He oversaw the construction of a church in Turin, Our Lady of Suffrage (Chiesa del Suffragio). His experience as a soldier, and his brother’s death, had greatly affected him and he held daily prayers in the church of Nostra Signora del Suffragio for the souls of all soldiers killed in wars. But, because he saw knowledge as sacred, and a way of gaining intimacy with God, he also set up a Foucault pendulum in the church he built, in order to demonstrate the rotation of the earth. He established Saint Joseph’s Hospital for the sick and convalescent (1860), a home for aged priests (1862), and classes for the vocational education of poor youth (1864). In 1866, he organised courses to train people to become elementary school teachers. He founded a society to provide help for maids and domestic servants, and insure their right to participate in Sunday liturgies. It was later expanding its outreach to include others, such as unmarried mothers.  He accomplished most of the above as a dedicated layman.

Despite the many long hours he spent undertaking charity work, Faà di Bruno did not ignore his mathematical research. He continued to publish articles and gained international fame as a mathematician. He made numerous important contributions to mathematics, being the author of about 40 original articles, Including Faà di Bruno’s formula on derivatives of composite functions. His students included Corrado Segre and Giuseppe Peano. Although he is usually remembered because of Faà di Bruno’s formula, his most influential mathematical work was his book Théorie des formes binaires on binary forms, published in 1876., based on lectures Faà di Bruno had given at the University of Turin.  Paul Gordan’s letter to Faà di Bruno praising the work, is in the Preface to Théorie des formes binaires:

I have had the opportunity to read your book on binary forms, and I was happy because I found it well adapted to introduce the reader to the theory of invariants. The subject is thoroughly and brilliantly set out, the exposition is simple, clear and, in several places, elegant. ... You have with this work delivered a service to science for which it will be grateful, since you have filled an important gap.

Faa di Bruno felt the call to the priesthood in his 40s, but the Archbishop of Turin would not let him begin due to his age. He appealed to Pope Pius XI, who allowed him to proceed in his studies. He was ordained in 22 October 1876 at the age of 51. The following month he opened the church he founded (Chiesa del Suffragio ) to the public (October 30) and celebrated his first Mass as Father Francesco (November 1). Five years later, in 1881, he founded the Minim Sisters of St. Zita. With the help of the Minim Sisters, he also established another refuge, one dedicated to taking in prostitutes. In order to provide work for the women, Faà di Bruno had the idea that they could train as typesetters. He purchased a printing press and set up the Tipographia Suffragio. There a number of mathematics books were published including one by Faà di Bruno himself on elliptic functions. He also spent his time in composing sacred melodies, several of which were praised by Franz Liszt. For his heroic virtues, Pope John Paul II beatified him in 1988.