On the hottest day of 2022 mercury levels in Berlin’s thermometers hit 37.5°C. That was the official reading. The unofficial ones – as in many places in the city the temperatures exceeded the latter – had both guests and residents perspire profusely and gasp for air in sizzling desperation. And by the look of it, with our climate spinning even further out of control, this year we are likely break that record.

What you need to survive such scorchers are, first and foremost, water plus protective headgear. The latter has, however, one significant disadvantage: most hats tend to develop sub-tropical conditions inside the crown. You sweat, you suffer and eventually you use the hat to fan yourself with in order to cool down the overheated scalp. But what if your headgear cannot be used for that purpose? If you cannot take it off or if frantic flapping fails to produce the desired cooling effect? A Berlin inventor, convinced he had solved that problem, applied for a patent as early as in 1878.

In the 1870s no respectable person ventured into the public space bareheaded. Only children and the poor would have been seen with no hat or bonnet in the streets. However, although a covered head might have been a marker of one’s social standing (those who could afford a hat, made sure to wear it) but, from the practical point of view, it could also be a blessing and a curse. While ladies’ hats tended to be rather “airy”, providing a tad more ventilation to the often highly decorative (and it itself rather tricky in the heat) hairdos, men’s hats caused their wearers’ scalps to swelter and sweat. The greatest culprit among those headpieces was at the same time the then sacred symbol of Prussian militarism: the Pickelhaube. Its wearers, clad in thick uniforms and marching up and down Berlin’s exercise fields, often ended up feeling unwell und even collapsing. The spring and autumn army manoeuvres on the Tempelhofer Feld (former site of the Tempelhof airport, where the largest Berlin park spreads today) were nothing for the weak-hearted…

According to Berlin’s 1879 address directory, potential help was to come from Admiralsstraße 15 in today’s Kreuzberg. The neighbourhood where Herr Niemann lived and worked, a stone’s throw from Kottbusser Tor, was also in a walking distance from several famous army barracks. It is, therefore, not unlikely that the engineer saw a sound business opportunity in his venture. Selling a functioning Pickelhaube ventilation system, or what Niemann described as Ventilationseinrichtung für Kopfbedeckung, to the Prussian military would have set him up for a lifetime. It is equally possible that Herr Niemann, professionally active in the field of ventilation anyway (sadly, History largely ignored the undoubtedly fascinating life of Gustav Niemann) simply wished to alleviate the pain of all profusely and uncontrollably sweating hat-wearers.

His invention was meant to offer relief in that air would be able better to circulate between the inside of the hat’s crown and the outside world. A small wind wheel or turbine – with ten wings made of a “light yet sturdy material” – was to be installed on top of the crown. The leather sweatband – which every Pickelhaube was fitted with to make it sit on the head firmly –  was to have small, approximately 1-centimetre wide sections carved out at regular intervals to create small openings. The leather sweatband would be held together by a cleverly inserted wiring. According to Herr Niemann’s computations, the rotating wind wheel inside the hat would have helped transport the “perspiratory vapours” outside, thus preventing draught inside the hat, “conserving” one’s hair and helping keep rheumatism, nausea and sunstroke at bay. As to whether it produced the desired effects, the patent offers no answers. The press, too, failed to report any potential triumphs.

Six months later two other gentlemen, Herr Block and Herr Günther, applied for a patent of their own. Registered under the number 6073 in the same category, it safeguarded the inventors’ rights to a “Sponge wreath – where but several drops of Schnaps [for soaking the sponge with, author believes] would be enough to lower the temperature through alcohol’s evaporation”. Did the sponge and the Schnaps help? Alas, yet again our curiosity must remain unfed and doubting. However, the Schnaps – in whichever form it might have been applied – was guaranteed to bring light, if temporary, relief to the sufferers.

And today? A quick search in the EPO (European Patent Office) databank shows that the exhausting race of human kind against the sweaty scalp has not been decided yet. However, with the next scorcher ante portas and no reliably functioning hat-ventilation in sight, remember: a glass of cold beer, enjoyed in the shade while fanning yourself with a just-read, folded newspaper is a perfectly reasonable alternative. And it’s completely patent-free.

An abridged German version of the text was published in Berlin’s most popular daily, the “Tagesspiegel”, where you will find my weekly (new stories each Saturday) Berlin-history column “Aus der Zeit”: Kühler Kopf 1878: Ein Belüftungssystem für die preußische Pickelhaube (tagesspiegel.de)