At the present time in this country scientific men are paid for teaching, lecturing, writing popular scientific articles, compiling scientific books, editing scientific journals, making chemical analyses and experiments for manufacturers, companies, and others, for practical purposes, or to obtain evidence for legal cases, giving evidence on scientific subjects in courts of law, with consultations and advice to manufacturers and others, superintending scientific commercial undertakings, &c. Some also unfortunately obtain an income and cheap publicity by the empirical contrivance of selling to tradesmen, their scientific opinions in the form of testimonials which are extensively {180} advertised at the cost of the purchasers. But not one of these occupations constitutes pure research, or is an immediate source of new discoveries. Payment is made for all kinds of scientific labour which will immediately benefit individuals or corporations, but very little for pure investigation, and nearly every inducement exists to attract men of science from pursuing such labour. It might be supposed that investigators would patent or sell their discoveries; but discoveries in pure science cannot usually be patented or sold, because they have not been converted by invention into commercial commodities. New scientific truth is utterly unsaleable; no one will purchase it. Whilst the real or intrinsic value of it is great, its extrinsic value is small and is the sum of money it will sell for in the market. No one would have purchased Oersted's great discovery of electro-magnetism. It would also be less to public advantage if investigators were to neglect discovering new knowledge in order to apply that knowledge to practical uses. It requires a different training of mental power to discover new truths, than to utilize them by means of invention, teaching or lecturing; and men who can invent and instruct are far more numerous than those who are able to discover. Discoveries are also generally much more valuable than inventions, because a single discovery (that of gutta percha for example) not unfrequently forms the basis of many inventions. Discoverers not unfrequently meet with new facts {181} which they perceive might be applied to valuable technical uses, but they hesitate to patent them because the process of invention, taking out a patent, seeking a manufacturer to work it, and protecting their patent from piracy, would occupy a large portion of their time, and take them away from research. Sir D. Brewster got no money by patenting his kaleidoscope because the patent was instantly pirated in all directions.