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,
Johannes Kuenen experiments with x-rays with the physiologist Edward Waymouth Reid. In 1907 he was appointed professor of physics at Leiden University. Heike Kamerlingh Onnes and Kuenen led the Kamerlingh Onnes physics Laboratory. On the basis of his scientific work he was elected in 1911 as a member of the Royal Netherlands Academy of Arts and Sciences (KNAW), and became a member of the Hollandsche Maatschappij der Wetenschappen in 1915. He discovered retrograde condensation and published his findings in 1892 in the Ph.D. thesis with the title "Metingen betreffende het oppervlak van Van der Waals voor mengsels van koolzuur en chloormethyl". (Measurements