Cartesian diver
A Cartesian diver (also: Cartesian diver , Cartesian dance devil , bottle devil , water devil or rotary devil ) is a hollow body filled with liquid and air that can be used as a toy or as a measuring device for the pressure in liquids . The name is derived from René Descartes , Latinized Cartesius . It was supposedly developed by René Descartes around 1640, but actually invented by Raffaello Magiotti and first described in 1648.
function
Raffaello Magiotti , 1648: A diver swims in the vessel on the left
Glassblower leaflet with an “amusement” that uses Cartesian divers, Wroclaw around 1670
The figure has a cavity that leads to the outside through an unlocked opening. This cavity is filled with water to such an extent that the buoyancy is just enough to prevent it from sinking, i.e. it just stays on the surface of the water. So it is put in a bottle filled as completely as possible with water, which z. B. is closed with a flexible rubber hat. Pressing the cap increases the pressure inside the bottle. This pressure is transmitted via the water to the diver and the volume of air it contains, which is then compressed. Because of the incompressibility of the water, the change in volume at the closure corresponds practically completely to the change in volume of the air in the diver.
By increasing the pressure, the air trapped in the body is compressed, so its volume decreases, and with it the buoyancy due to it, while the weight of the trapped air and the weight of the figure remain the same. If previously the amount of buoyancy just exceeded the amount of weight of the figure-air combination, this is now reversed and the buoyancy is smaller compared to the weight. This results in a downward force and the figure and its air content sink.
Conversely, when you let go of the lock, the pressure decreases and the volume of the air increases again. It expands by displacing some water, which increases the volume and thus the buoyancy again - the figure rises again.
With a little practice, the Cartesian diver can also be kept in suspension. A submarine corresponds to a Cartesian diver who is in unstable equilibrium .
toy
Cartesian diver; The hollow tail, curled around the body, is clearly visible, through which water flows into and out of the body of the diver
Cartesian diver; Glassblower work from Lauscha , Thuringian Forest
Cartesian diver as "dancing devil"
Cartesian diver
Cartesian divers that can be bought ready-made are made of blown glass and are approx. 3 cm long. At the lower end (usually on the devil's "tail") there is a small hole, the diver is placed in a plastic bottle filled with water. If you close the bottle now, the diver swims up. If you press the bottle, the diver sinks to the bottom.
A very simple Cartesian diver can be made from a piece of aluminum foil shaped into a ball (so large that it fits through a bottle neck). You may have to try something out and squeeze or pull the material apart until the aluminum ball has the right density. Many other objects that contain air and liquid are also suitable as a diver, such as: ink cartridges, baking oil bottles or plastic packets of ketchup or mustard, as well as match heads or pieces of fresh orange peel, as long as the gas bubbles they contain have not pearled out.
In the case of the glass Cartesian divers with a winding water inlet and outlet, the outflow of the pressed water causes a rotary movement around the body axis of the Cartesian diver, the diver climbs to the surface while turning.
literature
- Citizen Wolfgang (1995) Cartesian divers . In: The paradoxical egg cooker . Birkhäuser, Basel, pp. 132–145
- Kircher Athanasius (1654), Magnes Sive De Arte Magnetica Opus Tripartitum , Edition Tertia, Deuersin, Roma pp. 127–132
See also
Web links
- Building instructions for a Cartesian diver
- Interactive Java applet of a Cartesian diver (English)
- Carrasquer, J., Álvarez, MV, y Ponz, A. (2014). Exhibition "Dance, dance, you little devils" - A look at the history of the Cartesian divers in pictures
- Danese Beniamino (2013), Le caraffine di Magiotti
- Carrasquer, J., Ponz, A., Álvarez, MV y Uría, J. (2013), Historia de los nombres del Diablo Cartesiano ('On the history of the name of the Cartesian diver', Spanish), STUDIUM. Revista de Humanidades, 19, 75-96.
Individual evidence
- ^ A b Magiotti Raffaello (1648), Renitenza certissima dell'acqua alla compressione , Roma
- ↑ Cartesian diver. ( Memento of the original from February 7, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. FH Munich
- ↑ http://homepage.mac.com/mwey/skripts/Prak-03-Cartes-Tauchr.pdf ( Memento from April 30, 2004 in the Internet Archive )
- ^ Rebecca Hopman and Kathryn Wieczorek (2017), Making Cartesian Divers: Then and Now
- ↑ How does a bottle diver actually work? In: chemieunterricht.de
