About this same period mesmerism was again coming to the front, this time cloaked as a science termed electro-biology. Simpson acknowledged that there was a great deal in mesmerism demanding scientific investigation; but with his reasoning powers he could not realise the existence of the mystically-termed higher phenomena of animal magnetism, _e.g._, lucidity, transference of the senses, and, above all, clairvoyance. It happened that a professional mesmerist gave a performance in Edinburgh; learning that the "professor's" daughter was stated to be able to read anything written on paper, or to divine any object enclosed in a sealed box while under her father's mesmeric power, Simpson attended the performance. He took with him a specially-prepared test--a sealed box with certain unknown contents; this he presented at a suitable opportunity. Against their own wishes, but on the insistence of the audience, the performers made an attempt by their methods to detect the nature of the contents of this test-box. They pronounced it to be money; on opening it millet seed was found, and a piece of paper, on which was written, "humbug." An accusation, couched in bitter terms, that Simpson was really a supporter of mesmerism as it was then known, was published in one of the leading professional journals in London. He indignantly repudiated the suggestion and proposed to settle the matter finally by a simple expedient. He offered to place five sealed boxes each containing a line from Shakspeare written by himself on paper, in the hands of the editor of the journal who had permitted the attack to appear in his columns. To any clairvoyant who read these lines according to the professed method, and to the satisfaction of a committee of eminent medical men, he promised the sum of five hundred pounds. The offer, however, was not accepted. The brilliant attainments of many of its teachers at this period not only placed the Edinburgh school at the head of the British schools of medicine, but also led to tempting offers being made to individual professors by rival schools anxious to secure their services. London was a much more lucrative field for practice than the Scots metropolis, and several of the most eminent Edinburgh men had from time to time yielded to the temptation to migrate southwards. Indeed, London as a medical school owes a great deal to the Scotsmen whom she imported. Liston had left for London in 1834, and Syme followed, for a brief period, on Liston's death. In 1848 a strong effort was made to secure Simpson as a lecturer on midwifery at St. Bartholomew's Hospital; without any hesitation he decided to remain in the city where he had fought his way to fame, and where he enjoyed popularity, and a practice sufficiently lucrative to satisfy the most ambitious man. Every patriotic Scot applauded the decision.