Superconductivity and carbon nanotubes, are Type I, while almost all impure and compound superconductors are Type II. Conversely, a spinning superconductor generates a magnetic field, precisely aligned with the spin axis. The effect, the London moment, was put to good use in Gravity Probe B. This experiment measured the magnetic fields of four superconducting gyroscopes to determine their spin axes. This was critical to the experiment since it is one of the few ways to accurately determine the spin axis of an otherwise featureless sphere. Superconductivity was discovered on April 8, 1911 by Heike Kamerlingh Onnes, who was studying the resistance
Museum Boerhaave Museum Boerhaave Museum Boerhaave is a museum of the history of science and medicine, based in Leiden, Netherlands. The museum hosts a collection of historical scientific instruments from all disciplines, but mainly from medicine, physics, and astronomy. The museum is located in a building that was originally a convent in central Leiden. It includes a reconstructed traditional anatomical theatre. It also has many galleries that include the apparatus with which Heike Kamerlingh Onnes first liquefied helium (in Leiden), the electromagnet equipment used by Wander Johannes de Haas (a Leiden physicist) for his low-temperature research, and an example of the Leiden