Superconducting magnet issues "shaken" out of them, until they are eventually able to operate reliably at their full planned current without experiencing quenches. Although the idea of making electromagnets with superconducting wire was proposed by Heike Kamerlingh Onnes shortly after he discovered superconductivity in 1911, a practical superconducting electromagnet had to await the discovery of superconducting materials that could support large critical supercurrent densities in high magnetic fields. The first successful superconducting magnet was built by G.B. Yntema in 1955 using niobium wire and achieved a field of 0.7 T at 4.2 K. Then, in 1961, J.E. Kunzler, E. Buehler, F.S.L. Hsu,
Weiss magneton of the saturation magnetization at the temperature of liquid hydrogen in the laboratory of Heike Kamerlingh Onnes in Leiden. In 1911, Weiss announced that the molar moments of nickel and iron had the ratio of 3:11, from which he derived the value of a magneton. Weiss gave an address about the magneton at a conference in Karlsruhe in September 1911. Several theorists commented that the magneton should involve Planck's constant "h". By postulating that the ratio of electron kinetic energy to orbital frequency should be equal to "h", Richard Gans computed a value that was almost an order of magnitude