PROFESSOR ONNES AND THE LEIDEN LABORATORY OF PHYSICS
The Franklin Institute has made the first awards of its Franklin medal, established last year by a gift from Mr. Samuel Insul, to Mr. Thomas Alva Edison and to Professor Heike Kamerlingh Onnes. Mr. Edison's great contributions to the applications of science are known to us all. It may be of interest to give some statement of the work of Professor Onnes and the Leiden Laboratory, taken from the report of the institute. At the present time it is well to remember the important contributions made to science by the smaller nations. It is certainly a remarkable fact that Holland should have more physicists of high distinction than the United States.
Heike Kamerlingh Onnes was born on September 21, 1853, at Groningen, Holland, where his father was engaged in manufacture. He was educated in the schools of his native town, and there also he began his university studies in 1870. Two years later he removed to Heidelberg, where he spent three semesters, working under the direction of Bunsen and Kirchoff. He then returned to Groningen, and a few years after he became assistant to Professor Bosscha at Delft, where he commenced work upon his thesis for the doctorate. In 1882 he and H. A. Lorentz were appointed professors of physics in the University of Leiden, then a little known and quite unpretentious seat of learning (so far as physical science was concerned), but which, as a result of the collaboration of these two highly-gifted young physicists, has become one of the world's great centers of physical research.
While Lorentz confined his energies mostly to the fields of theoretical and mathematical physics, Onnes directed his energies to the creation of a laboratory for experimental research. In spite of great obstacles, particularly of very inadequate appropriations for equipment and maintenance, the indefatigable director found ways and means of furnishing his laboratory with the special machinery and precision instruments required for the researches of the professors and their students. A very important—in fact, an essential—factor in this development was the establishment by Onnes of a training school for mechanicians, and it was in the shops of this school that many of the special instruments for the laboratory were constructed. At the same time the young men engaged there were trained to assist the director in carrying out the often difficult and intricate operations in his experimental work. On various occasions Professor Onnes was thus enabled to command a force of some thirty assistants, to each of whom a special duty was assigned.
The work of this great laboratory at Leiden is recorded in the Leiden Communications, published since 1891, and includes a vast number of most important contributions to physical science. Among them are investigations on magneto-electric effects, as well as a series of most important papers upon magneto-optical phenomena, such as the classical one by Zeeman, describing the discovery of what is now known as the Zeeman-effect. But, while these early investigations were all carried out under Onnes's direction, they were in many cases inspired or suggested by his distinguished colleague, H. A. Lorentz. The really representative work of the laboratory has been in the field of molecular physics, and particularly in research at low temperature. The great bulk of the Leiden Communications is devoted to the records of those remarkable series of researches which were conceived by Onnes himself and carried out under his direction.
The history of these researches began with the creation of the cryogenic laboratory, and it may be divided into several distinct stages or periods. The first of these was occupied with the production of liquid oxygen on a large scale, and with the use of this material in a three-cycle process of obtaining