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
Leiden if there's a Sunday involved) and includes parades, a hutspot feast, historical reenactments, a funfair and other events. The city has recently started to host the Leiden International Film Festival, the fastest growing festival of its type in the Netherlands. Leiden has important functions as a shopping and trade centre for communities around the city. The University of Leiden is famous for its many discoveries including Snells law (by Willebrord Snellius), the famous Leyden jar, a capacitor made from a glass jar, invented in Leiden by Pieter van Musschenbroek in 1746. Another development was in cryogenics: Heike Kamerlingh Onnes (1913