He began his novitiate in the Society of Jesus at Bahia when he was about fifteen years old, but left the same in 1701. He went to Portugal and found a patron at Lisbon in the person of the Marquess d'Abrantes. He completed his course of study at Coimbra, devoting his attention principally to philology and mathematics, but received the title of Doctor of Canon Law. He is said to have had a remarkable memory and a great command of languages.
In 1709 he presented a petition to King John V of Portugal, begging a privilege for his invention of an airship, in which he expressed the greatest confidence. The contents of this petition have been preserved, as well as a picture and description of his airship. Following after Francesco Lana, S.J., Gusmão wanted to spread a huge sail over a bark like the cover of a transport wagon; the bark itself was to contain tubes through which, when there was no wind, air would be blown into the sail by means of bellows. The vessel was to be propelled by the agency of magnets which, apparently, were to be encased in two hollow metal balls. The public test of the machine, which was set for June 24, 1709, did not take place. According to contemporary reports, however, Gusmão appears to have made several less ambitious experiments with this machine, descending from eminences. His contrivance in the main represented the principle of the kite (aeroplane). In all probability he did not have magnets in the aforementioned metal shells, but gases and hot air generated by the combustion of various materials.
It is certain that Gusmão was working on this principle at the public exhibition he gave before the Court on August 8, 1709, in the hall of the Casa da India in Lisbon, when he propelled a ball to the roof by combustion. The king rewarded the inventor by appointing him to a professorship at Coimbra and made him a canon. He was also one of the fifty chosen members of the Academia Real da Historia, founded in 1720; and in 1722 he was made chaplain to the Court. He busied himself with other inventions also, but in the meantime continued his work on his airship schemes, the first idea for which he is said to have conceived while a novice at Bahia. His experiments with the aeroplane and the hot-air balloon led him to conceive a project for an actual airship, or rather a ship to sail in the air, consisting of a cleverly designed triangular pyramid filled with gas, but he died before he was able to carry out this idea.
The fable about the Inquisition having forbidden him to continue his aeronautic investigations and having persecuted him because of them, is probably a later invention. The only fact really established by contemporary documents is that information was laid against him before the Inquisition, but on quite another charge. He fled to Spain and fell ill of a fever, of which he died in Toledo. He wrote: Manifesto summario para os que ignoram poderse navegar pelo elemento do ar (1709): Varios modos de esgotar sem gente as naus que fazem agua (1710); some of his sermons also have been printed.
Biographie Universelle, XIX (Paris, 1817), 218-220; Carvalho, Memoria que tem por objecto revindicar para a nação portugueza a gloria da invenção das machinas aerostaticas (Lisbon, 1843); Simões, A invenção dos aerostatos reivindicada (Evora, 1868); Moedebeck, Zeitschrift für Luftschiffahrt (1893), 1-10; João Jalles, Os balões (Lisbon, 1887); Wilhelm, An der Wiege der Luftschiffahrt, Pt. II (Hamm, Westphalia, 1909).
From the Catholic Encyclopedia, 1910