From this point onward the interest of Maxwell's life (save things “wherewith the stranger intermeddles not”) is chiefly concentrated in his scientific career. As some account of his labours in science will be given in the second portion of this book, what remains of the present narrative is comparatively brief.

1860-1865. Æt 29-34.

The work at King's College was more exacting than that in Aberdeen. There were nine months of lecturing in the year, and evening lectures to artisans, etc., were recognised as a part of the Professor's regular duties. Maxwell retained the post until the spring of 1865, when he was succeeded by Professor W. Gr, Adams, but continued lecturing to the working men during the following winter.

In June 1860 Maxwell attended the British Association's meeting at Oxford, where he exhibited his box for mixing the colours of the spectrum. He also presented to Section A a most important paper on Bernoulli's Theory of Gases; a theory which supposes that a gas consists of a number of independent particles moving about among one another without mutual interference, except when they come into collision. Maxwell showed that the apparent viscosity of gases, their low conductivity for heat, and Graham's laws of diffusion, could be satisfactorily explained by this theory, and gave reasons for believing that in air at ordinary temperature each particle experiences on an average more than 8,000,000,000 collisions per second.