Gaiety is just beginning here again.... No jokes of any kind are understood here. I have not made one for two months, and if I feel one coming I shall bite my tongue. But every cloud has its bright side, and, however Maxwell may have been regarded by his colleagues, he was not long without congenial companionships. An honoured guest at the home of the Principal, "in February, 1858, he announced his betrothal to Katherine Mary Dewar, and they were married early in the following June." Professor Campbell speaks of his married life as one of unexampled devotion, and those who enjoyed the great privilege of seeing him at home could more than endorse the description. In 1860 Maxwell accepted the chair of Natural Philosophy at King's College, London. Here he continued his lectures to working men, and even kept them up for one session after resigning the chair in 1865. On May 17, 1861, he gave his first lecture at the Royal Institution, on "The Theory of the Three Primary Colours." This lecture embodies many of the results of his work with the colour-top and colour-box, to be again referred to presently. While at King's College, he was placed on the Electrical Standards Committee of the British Association, and most of the work of the committee was carried out in his laboratory. Here, too, he compared the electro-static repulsion between two discs of brass with the electro-magnetic attraction of two coils of wire surrounding them, through which a current of electricity was allowed to flow, and obtained a result which he afterwards applied to the electro-magnetic theory of light. The colour-box was perfected, and his experiments on the viscosity of gases were concluded during his residence in London. These last were described by him in the Bakerian Lecture for 1866. After resigning the professorship at King's College, Maxwell spent most of his time at Glenlair, having enlarged the house, in accordance with his father's original plans. Here he completed his great work on "Electricity and Magnetism," as well as his "Theory of Heat," an elementary text-book which may be said to be without a parallel.