The name of “applied science” is quite misleading, because, in the great majority of cases, invention, far from being an application of science, on the contrary creates a new branch of science. The American bridges were no application of the theory of elasticity; they came before the theory, and all we can say in favour of science is, that in this special branch, theory and practice developed in a parallel way, helping one another. It was not the theory of the explosives which led to the discovery of gunpowder; gunpowder was in use for centuries before the action of the gases in a gun was submitted to scientific analysis. And so on. One could easily multiply the illustrations by quoting the great processes of metallurgy; the alloys and the properties they acquire from the addition of very small amounts of some metals or metalloids; the recent revival of electric lighting; nay, even the weather forecasts which truly deserved the reproach of being “unscientific” when they were started for the first time by that excellent observer of shooting stars, Mathieu de la Drôme, and by an old Jack tar, Fitzroy--all these could be mentioned as instances in point. Of course, we have a number of cases in which the discovery, or the invention, was a mere application of a scientific law (cases like the discovery of the planet Neptune), but in the immense majority of cases the discovery, or the invention, is unscientific to begin with. It belongs much more to the domain of art--art taking the precedence over science, as Helmholtz has so well shown in one of his popular lectures--and only after the invention has been made, science comes to interpret it. It is obvious that each invention avails itself of the previously accumulated knowledge and modes of thought; but in most cases it makes a start in advance upon what is known; it makes a leap in the unknown, and thus opens a quite new series of facts for investigation. This character of invention, which is to make a start in advance of former knowledge, instead of merely applying a law, makes it identical, as to the processes of mind, with discovery; and, therefore, people who are slow in invention are also slow in discovery.