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,
Floris Verster 1880 and 1884 Verster continued his training at the Royal Academy of Art in The Hague where he counted among his fellow-students George Hendrik Breitner, Isaac Israëls and Willem de Zwart. After graduation, he briefly attended classes at Amedee Bourson in Brussels. From 1882-1892 he shared a studio in Leiden with his future brother-in-law, the still-life painter Menso Kamerlingh Onnes (he married Jenny Kamerlingh Onnes in 1892). Until about 1885 he worked in the style of the Hague School. The next seven years he experimented in still life painting under the influence of his brother-in-law and of French painters Antoine