Maria Christina Bruhn was a Swedish inventor and the owner of a workshop where she invented a particular type of gunpowder cartridge for the Swedish artillery during the eighteenth century.
Maria Christina Bruhn was born in Stockholm in 1732. Her father Johan Bruhn was a bookkeeper at the Charta Sigillata office. Maria Christina was the eldest of three sisters: her sister Ingrid was born in 1737 and Eva followed in 1741. Their father died the following year. Three weeks after his death, their mother was awarded a licence from Kommerskollegiet (National Board of Trade) allowing her to establish a wallpaper manufacturing business. This meant she could call herself a manufacturer. Maria Christina was 19 years old when her mother died in 1751 and she then took over the wallpaper manufacturing business, as well as full responsibility for her younger sisters.
Maria Christina Bruhn ran the wallpaper business and also trained her sisters. The town surveyor Hieronymus von der Burg – also known for being one of the botanist Carl von Linné’s apprentices – lived in the building which housed the wallpaper workshop. Maria Christina’s sister Ingrid started a relationship with von der Burg which resulted in Ingrid becoming pregnant. Ingrid and Hieronymus got married in April 1766. Through this marriage Maria Christina gained access to a network of contacts which included the educated elite of Stockholm. Nils Lindblom, professor of mathematics for the artillery, and Pehr Lehnberg, professor at the artillery cadet school, both belonged to this network, and both of them came to play significant roles in Maria Christina Bruhn’s life.
In 1773 the Swedish king announced a competition with a prize of 6000 daler copper coin as a reward for the best invention to store gunpowder in a “fastage” or in a “kardus”. A “fastage” was a type of layered barrel whilst the “kardus” was a gunpowder cartridge made of either cloth or paper, which was used to prime canons. The “kardus” was not only required to keep gunpowder both dry and safe from catching fire but it was also needed in order to not leave live embers in the canon once it was spent. The Royal Academy of Sciences was commissioned to judge every suggestion received.
Once Maria Christina Bruhn heard about this royal announcement she immediately set about attempting to construct the perfect cartridge – possibly using the good advice of her contacts, including the artillery school professors. She created cartridges out of paper which she then varnished. On 2 March 1774 she had the opportunity of presenting her cartridges to the Royal Academy of Sciences, where they were studied by Professor Lindbom and Professor Lehnberg who ordered that they be test-fired under the supervision of Major General Charpentier. This took place in the autumn of 1774 and, according to the reports, the results were more or less positive. Maria Christina Bruhn was not the only person to respond to the royal call for prototypes, however. General of the artillery Reinhold von Anrep had also presented a cartridge which had similarly been test-fired with variable results. In reality both prototypes were declared unfit. As these had been the top two candidates the project was then abandoned.
Maria Christina Bruhn’s test-cartridges had left residues in the canon which had blocked the barrel. This was an easily resolvable problem, however, which simply required that the end of the cartridge be covered with a thin layer of woollen material. Right up until 1780 Maria Christina Bruhn delivered these updated versions of her varnished cartridges at her own expense for use by the artillery cadets in their exercises without any untoward accidents.
Major Per Gustaf Wagenfelt had been present at the test-firing of Maria Christina Bruhn’s cartridges. In 1781 he successfully obtained a royal salary of 500 riksdaler for inventing varnished cartridges, which he kept entirely for himself. When this was published in Stockholms Posten in 1783 Captain Lindfeldt complained to the Krigskollegium (the military board) that he had played an equal part in the invention and that Wagenfelt had only been taught how to use the secret cartridge invention in 1774 on condition that he did not disclose it.
Maria Christina Bruhn also recognized the description of the cartridges as those she had invented and she also made a case before the king. This led to an investigation in which all those involved tried to feign ignorance whilst not impugning anyone else. In the meantime the truth behind the cartridges could not be suppressed. In August 1786 the Krigskollegium proclaimed that Maria Christina Bruhn’s cartridges were the best and the most affordable, and that she had thus won the competition. Following the monetary reform of 1777 the prize total was re-evaluated at 333 riksdaler and 16 shillings. On 8 May 1787 Maria Christina Bruhn obtained a receipt for half of that sum for the cartridges, namely 166 riksdaler and 32 shillings in coin. She then closed her wallpaper workshop and retired. She managed to live her life out on her prize money, combined with maintenance money she received from the Drake estate. She died on 20 October 1808, aged 77.