esting metaphysical speculation. But the authors proceeded further to apply their speculation, to explain the main doctrines of Christianity. Hypotheses about the nature of matter may change, and have changed wonderfully since 1875, and no one cares to see sacred truths placed on so precarious a foundation as the vortex theory of matter.
Such was the immediate success of the book, from the point of view of sales, that the authors were induced to venture on a novel Paradoxical Philosophy: a Sequel to the Unseen Universe. The hero is a Dr. Stoffkraft, who goes to Strathkelpie Castle to take part in an investigation of spiritualistic phenomena. He begins by detecting the mode in which one young lady performs her spirit-rapping, but forthwith falls into an "electrobiological" courtship of another, and, this proving successful, he is persuaded by his wife and her priest to renounce the black arts in the lump as works of the devil; and then settles down to compose an "Exposition of the Relations between Religion and Science," which he intends to be a thoroughly matured production. He advocates various materialistic views, but the other guests at the castle, who compose the Paradoxical Club, have read The Unseen Universe, and work discomfiture on Dr. Stoffkraft by arguments drawn from it.
About this time, 1876, Tait published a volume entitled Lectures on Recent Advances in Physical Science. These lectures, prepared at the request of a number of professional men, chiefly engineers, were delivered in the physics theater of the University. They were edited from the report of a stenographer, and they give a very good idea of Tait's style as a lecturer. He was in his time considered the finest lecturer of the Edinburgh University. On reading these lectures, published only twenty-five years ago, one is struck by the greatness of the advances made since, especially in the domain of electricity. In them there is no mention of the telephone or microphone, of the dynamo or incandescent lamp; electric waves and X-rays are yet undemonstrated. The advances treated of are the doctrine of energy, spectrum analysis, the conduction of heat, and the structure of matter. Prof. Tait was accustomed
