As early as the 1670s, itinerant glassworkers were touring Europe demonstrating lampworking techniques to curious onlookers. A Dutch glassworker used this handbill to advertise his show in Wrocław, Poland, where he demonstrated at the Golden Sword (likely an inn or tavern). There, in the afternoons, the glassworker made glass eyes, weather-measuring devices, pots, bottles, and figurines.
He also displayed a relatively new scientific experiment: a Cartesian diver. The diver, seen in full on the right above, was created to demonstrate the relationship between density and buoyancy. But the Dutch glassworker didn’t explain the science behind the Cartesian diver to his audience. Instead, he treated it as a magic trick, in which the demonstrator commanded the figures in the bottle to move up and down by calling out orders. In reality, he used his hand to add or remove pressure from the air-tight membrane at the top of the vessel.
The glassworker included several figurines in his bottle: a toasting man, a queen, and what looks like perhaps a bear or a devil. (Cartesian divers were also know as Cartesian devils, water devils, and bottle imps.)
Tools of the trade
The handbill shows that this glassworker used a lamp similar to the one described by Johannes Kunckel in his 1679 translation of L’Arte vetraria (The Art of Glass). The flame was likely fueled by oil or tallow pulled through a cotton wick and the glassworker could shape and direct the flame using forced air (either supplied by the use of bellows hidden under the table or by blowing into a pipe directed at the flame). This glassworker also used a small blowpipe to make his products.
The glassworker offered to demonstrate at private residences upon request, and sold his products to interested observers. There is no price listed to see the show, which matches with other known advertisements from the period.