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
Frans Michel Penning of Gorinchem on 12 September 1894. Penning attended the University of Leiden. He studied mathematics and physics as a graduate student under Heike Kamerlingh Onnes. Penning's doctoral work involved measuring thermodynamic properties of various gases at extremely low temperatures. Penning received his PhD on June 25, 1923 with a dissertation entitled 'Metingen over isopyknen van gassen bij lage temperaturen' (Measurements on Isometric Density Lines of Gases at Low Temperatures). His father Louwrens Penning, was a popular novelist in the Dutch literary community; most known for romanticizing the Anglo-Boer War. His mother was Adriana Jenneke Machelina Heijmans. Penning married to Margje