Maria Christina Bruhn was Sweden’s first female inventor in the field of military technology. She improved the design of powder charges for cannons – so-called cartouches.
At the beginning of the reign of Gustav III, a large reward was announced for anyone who could invent a way of improving the ways in which gunpowder was handled. This involved both the barrels in which gunpowder was stored and the cartouches, which were a kind of paper or cloth bag that contained the powder charge inside the cannons. It was crucial that the barrels and the cartouches provided the gunpowder with adequate protection against both moisture and heat. For the cartouches, it was also vital that they did not cause a blockage or leave any residue inside the bore once the shot had been fired.
Maria Christina Bruhn (1732–1808) ran a tapestry and wallpaper workshop and was accustomed to working with paper, fabrics and varnish – knowledge that could easily be applied to the manufacturing of cartouches. Her sister had married the engineer Hieronymus von der Burg, who had studied under Carl Linnaeus and knew many influential scholars in Stockholm. Through him, Bruhn came into contact with Nils Lindholm and Pehr Lehnberg. Aside from being professors working for the military, they were also members of the Royal Swedish Academy of Sciences, which was to assess the entries to the competition announced by the king. It is likely that this is how Bruhn first heard about the competition. She left the manufacture of gunpowder barrels to others, but she believed that her background with wall coverings would make it possible for her to improve the design of cartouches.
Test-firing and skulduggery
On 2nd March 1774, Maria Christina Bruhn presented her invention to the Royal Swedish Academy of Sciences: the waterproof and fireproof varnished cartouche. The Academy organised a test-firing of her cartouches. The test-firing had creditable results but, unfortunately, the cartouche had left some residue inside the cannon, resulting in the bore becoming blocked.
Her main competitor was Reinhold von Anrep, who was General of the Artillery. The test-firing of his cartouches was even less successful. As neither submission was fully satisfactory, both were rejected, and the competition ground to a halt.
Bruhn began to modify her invention by adding a thin piece of fabric to one end of the cartouche. At her own expense, she supplied her cartouches to the cadet corps for their military exercises until 1780, without experiencing any problems.
Now, however, others began to take credit for her cartouches. One person who had been present at the test-firing of Bruhn’s cartouches was Major Per Gustaf Wagenfelt. He now presented the cartouches as his own, for which he received a royal reward of 500 riksdaler. When this became known, a certain Captain Lindfeldt – who knew that the cartouches were not Wagenfelt’s own invention – protested, and the whole affair subsequently became known to Bruhn.
In 1783, she wrote to the War Office to claim her rightful credit as well as the prize money. The wheels of bureaucracy turned slowly, but she did not give up. Not wishing to be seen to cast aspersions on the reputation of important figures, most of those involved attempted to wash their hands of the matter, but Bruhn persisted and eventually the truth about her cartouches could no longer be ignored.
After many letters, claims and counterclaims, the final decision came three years later. In August 1786, the War College ruled that it was Maria Christina Bruhn’s cartouches that were both the best and the cheapest, and that she was the true winner of the competition. On 8th May 1787, she received her reward. She then closed her tapestry and wallpaper workshop and returned to her private life. Maria Christina Bruhn died in 1808.
The size of the prize
It has often been claimed that Maria Christina Bruhn received only a fraction of the prize money to which she was truly entitled. This is, however, untrue. The total sum of the prize in 1773 (when the competition was announced) was 6,000 daler kopparmynt for the development of both the gunpowder barrel and the cartouche – i.e. 3,000 daler kopparmynt for the development of the barrel and 3,000 daler kopparmynt for the development of the cartouche.
Following the monetary reform of 1777, riksdaler (specie) became the main currency, which was worth 18 daler kopparmynt. One riksdaler was equivalent to 48 skilling. After the monetary reform, the total prize sum was stated to be 333 riksdaler and 16 skilling. On 8th May 1787, Maria Christina Bruhn accepted her half of the prize, which amounted to 166 riksdaler and 32 skilling (specie).
Text and research: Peter Du Rietz
Erik Lönnroth: “Mamsell Bruhn : en svensk uppfinnare i artilleriteknik” (1991) Included in: Polhem – Göteborg: Svenska nationalkommittén för teknikhistoria (SNT), 1991 (9), pp. 308-328.