Everyone knows that to discuss the history of fireworks means talking about China and Marco Polo (1254-1324), but the real history of fireworks in the European Middle Ages may start with Roger Bacon (1214-1294).
Bacon was a Franciscan Friar who spent time at Oxford and may have studied under Robert Grossteste. He has been called the first user of the scientific method, but more careful study of his works suggests that his conclusions and theories were the result of "thought experiments" like many other scholars, instead of actual scientific experimentation. Although Oxford's fairly careful and complete records of degrees given do not show that Bacon ever earned a doctorate, he was nicknamed Doctor Mirabilis (wonderful doctor) for his ideas.
Many volumes have been filled about Bacon, his ideas and discoveries, but today we are interested in gunpowder. At the request of Pope Clement IV, Bacon wrote his seven-part Opus Maius (Greater Work) which discussed (among other things) his thoughts on philosophy, theology, and certain scientific experiments. We know that a contemporary and fellow Franciscan, William Rubruck (c.1220-c.1293), visited the Mongols and witnessed the use of gunpowder in the form of firecrackers. Perhaps Rubruck brought some back. The relevant passage in the Opus Maius is:
We have an example of these things (that act on the senses) in that children's toy which is made in many [diverse] parts of the world; i.e. a device no bigger than one's thumb. From the violence of that salt called saltpetre [together with sulphur and willow charcoal, combined into a powder] so horrible a sound is made by the bursting of a thing so small, no more than a bit of parchment [containing it], that we find [the ear assaulted by a noise] exceeding the roar of strong thunder, and a flash brighter than the most brilliant lightning.The "no more than a bit of parchment containing it" reminds me of these. He speaks of this again in his Opus Tertium (the Third Work; and yes, there had been an intermediate Opus Minus, the Lesser Work):
Then wonders can be done by explosive substances. There is one used for amusement in various parts of the world made of powder of saltpeter and sulphur and charcoal of hazelwood. For when a roll of parchment about the size of a finger is filled with this powder, it produces a startling noise and flash. If a large instrument were used, the noise and flash would be unbearable; if the instrument were made from solid material, the violence would be much greater.These are the earliest references in the English-speaking world to gunpowder and fireworks. Whether Bacon ever made his own gunpowder is unknown, however. Some articles will tell you that he could, and encrypted the knowledge in order to prevent its misuse. Claims that Bacon hid the formula for gunpowder in his works cannot be substantiated, however. He seems to know what goes into the formula, but not necessarily in what proportion. The secret numbers that some modern manuscript detectives claim to have found in his writings produce the wrong ratio for gunpowder to do more than smoke.
Enjoy your day.