gutta-percha and india-rubber were indispensible to the great applications of those substances in telegraph cables, and in a multitude of useful articles. The discovery of chloroform and anæsthetics has led to their use for the purpose of alleviating human suffering. The discovery, by Sir Isaac Newton, of the decomposition of light by means of a prism, has led in recent times to the invention of the spectroscope; to the use of that instrument in the Bessemer steel process; to the discovery of a number of new metals, thallium, rubidium, cæsium, indium, and several others, and to the most wonderful discovery of the composition of the Sun and distant heavenly bodies. Even the invention of the steam-engine was partly a consequence of previous researches made by scientific discoverers. Watt, himself, stated in his pamphlet, entitled "A plain Story," that he could not have perfected his engine had not Dr. Black and others previously discovered what amount of heat was rendered latent by the conversion of water into steam. "Each mechanical advance in the steam-engine has been preceded by and the result of the {18} discovery of some physical law or property of steam." "The first step in the invention of the steam-engine was the experimental research and the discoveries of the properties of steam by Hooke, Boyle, and Papin."[2] Had not the steam-engine been developed, it is clear that railways, steamships, machinery, and all the other numerous uses to which that instrument is now applied, would have been almost unknown. The introduction of the steam-engine enabled abandoned Cornish mines to be relieved of water, and to be worked to much greater depths. The discoveries of nitric acid, hydrochloric acid, oil of vitriol, and washing soda, by the alchemists and early chemists in their researches, led to the erection of the numerous great manufactories of those substances which now exist in England and in other civilized countries. There is probably not an art, manufacture, or process, which is not largely due to scientific discovery, and if we trace them back to their source we nearly always find them originate in scientific research. So far has scientific discovery, and its practical applications to human benefit by invention, now progressed, that every one considers this to be, _par excellence_, the scientific age. And as discovery and invention continue to progress with accelerated speed, we are encouraged to hope, not only that scientific principles will ultimately be universally recognised as {19} the regulators of all technical industry, but also as a fundamental basis of morality.[3]