Thomson's agenda

Prior to his appointment as Cavendish Professor, Thomson was uncertain about his ability to sustain a career in experimental physics and had the option of concentrating on theoretical studies. Once his appointment was announced, however, he put all his energies into fostering the experimental activities of all his colleagues in the Laboratory and developing his own experimental agenda through the appointment of an expert laboratory assistant, whose salary he paid from his own pocket. Ebeneezer Everett was appointed to this post in 1888 and was to remain until 1930 when he retired due to ill health. In his touching obituary of Everett, published in Nature in 1933, Thomson wrote:

For many reasons, 1895 was a turning point in the development of the Laboratory and so it is illuminating to list the titles of Thomson's papers up until that year (Table 6.1). It is apparent that his interests were wide-ranging, but increasingly there was a strong emphasis upon the conduction of electricity in gases, which dates back to his paper of 1883, the year before he was appointed to the Cavendish Chair. Before looking in more detail into these researches, let us review the role of analogy and model-building as tools for the understanding of physical phenomena.

Analogy andmodel-building

A distinctive feature of Maxwell's approach to the application of mathematics to natural philosophy was his ability to work by analogy. As early as 1856, when he was in his mid-20s, he described his approach in an essay entitled Analogies in Nature, written for the Apostles Club at Cambridge (Maxwell, 1856a). The essence of the technique can be caught in the following passage.