geographical position, etc., etc. have, however, also contributed to the result. Commerce also in its turn has done vast things for mankind.
The purely scientific knowledge we possess was discovered almost entirely by means of original research, and to only a small extent by persons engaged in industrial occupations. Probably not two per cent. of all the important discoveries in pure science were made in manufactories; the scientific experiments which are made in such establishments are usually of the nature of invention, not of discovery, and are not often published, because it is a usual object with men of business to retain as much as possible of the pecuniary benefit of their labours to themselves. Whilst it is the object of a business man to monopolise special knowledge; that of the scientific man is to diffuse it, in order that all mankind may be benefited and helped to improve.
Discoveries in science are, however, occasionally made by practical men engaged in technical employments. The hydro-electric machine originated in this way, a man at Newcastle was attending to a steam boiler, and found that he received electric shocks when he touched the boiler. This circumstance was investigated by his employer, Mr. Armstrong, a scientific man, and led him to construct the hydro-electric machine. The accumulation of electricity in submarine telegraph cables was first observed at the Gutta-Percha Company's works
London. It was noticed on testing a cable by means of a voltaic battery (the cable being submerged in water) that discharges of electricity flowed from the cable after the battery was removed; this circumstance was investigated by Faraday, and led to improvements in submarine telegraphy. In each of these instances the same general method as that used by scientific discoverers was however employed, viz., new experiments were made (though not intentionally) by putting matter and its forces under new conditions, and new results were observed.
Nearly all great modern scientific discoveries have been made by teachers of science and others, who spend a large portion of their lives in experimental investigation, searching for new truths, and not by persons who have hit upon them by accident. The greatest discoveries in physics and chemistry in modern times, were made chiefly by such men as Newton, Cavendish, Scheele, Priestley, Oersted, Volta, Davy and Faraday: all great workers in science.
It is either by observing matter and its forces under new conditions or from a new aspect, that nearly all discoveries are made; thus Priestley placed some oxide of mercury in an inverted glass vessel, and heated it by means of the Sun's rays and a lens, and discovered Oxygen. This substance was nearly discovered by Eck de Sulsbach three hundred years before; he heated six pounds of an amalgam
of silver and mercury, and converted the latter metal into a red oxide like cinnabar, and he remarked, "a spirit is united with the metal, and what proves it is this, that this artificial cinnabar submitted to distillation, disengages that spirit." The "spirit" was evidently oxygen.
Some discoveries are made by observing the phenomena of bodies placed under special conditions by those operations of nature over which we have little or no control. All our knowledge of Astronomy, and much of that of geology and physiology, was acquired in this way.
Nearly all modern discoveries of importance in physics or chemistry require long and difficult investigations to be made in order to completely establish their truth. When Crookes discovered Thallium, he saw the first sign of its existence in a momentary flash of green light in a spectroscope, but he had to expend upon the subject several years of most difficult labour, and a considerable sum of money, in order to prove the correctness of his suspicion that he had discovered a new metal. M. Lecocq de Boisbaudran discovered the metal Gallium and Bunsen discovered Rubidium and Caesium in a similar manner.
Discoveries in science, are usually made, not by trying to obtain some valuable commercial or technical result, but by making new, reliable, and systematic investigations. By investigating the chemical action of electricity upon saline bodies,