The date of this engraving is unknown, and some details remain open to debate. What is certain is that it is a copy of a drawing originally attached to a 1709 manuscript, showing the flying machine proposed by Father Bartolomeu Lourenço de Gusmão. The original was lost, and this copy was published in 1868.
According to Carlos Fiolhais, former director of the University of Coimbra General Library, the image may offer a more realistic scale for a human-sized spherical balloon, though it is still far from flight-ready. Fantastical illustrations like these may have been deliberately created to intrigue onlookers while keeping the true design of the flying machine, which took off in Lisbon before the king, the court, and the papal envoy, a secret.