RESUMO
On the 10 July 1908 Heike Kamerlingh Onnes succeeded in the first liquefaction of helium. A very long preparation was necessary before Onnes succeeded. The underlying technological framework from his predecessors was mainly formed by the ingenious discoveries of Dewar. Onnes started with his cascade process of air liquefaction in 1892. In 1898 Dewar liquefied hydrogen for the first time and in 1906 the large hydrogen liquefier of Onnes was ready for use. The main part of this review concerns the first liquefaction of helium, for which the preparation of helium gas from monazite sand was needed, the construction of the liquefier and the mercury compressor of Cailletet, eventually rewarded with the first successful liquefaction. Subsequently, the later developments will be reviewed, i.e. Simon's expansion apparatus (1932), the helium liquefier of Kapitza (1934), and finally the Collins liquefier (1940-1947). This concludes the first half of the history of low temperature physics, after which a new area starts.
