The first utilization of Oersted's discovery in a concrete and practically usable device was the galvanometer, invented by Schweigger in 1820. It was a brilliant invention, and solved perfectly the important problem of measuring accurately the strength of an electric current. The apparatus consisted merely of a means of multiplying the effect of the deflecting current by winding the conductor into a coil, the magnetic needle being within the coil. The galvanometer (named after Galvani) was an invention of the utmost value, and it is in use to this day, though in many modified forms. When one realizes how obvious a utilization of Oersted's discovery the galvanometer was, and that Schweigger did not invent it until two years later, he wonders why Oersted himself did not invent it. But the history of invention is full of such cases and of cases still more amazing. Why did the world wait several thousand years before Wise invented the metal pen? Why are we not now inventing a great many more things than we are? Nature is holding out suggestions for inventions to us by the million, but we do not see them. In the year before Schweigger's invention, in 1821, the important discovery had been made by Seebeck in Berlin, that if two different metals are joined at their ends, and one junction be raised to a higher temperature than the other, a current of electricity will be generated, the strength of which will vary with the metals employed and the difference in temperature of the junctions. The discovery was soon utilized in Nobili's invention of the thermopile in which the current was increased by employing several layers of dissimilar metals (say antimony and bismuth) in series with each other. The main use of the thermopile has been in scientific investigations, especially in the science of heat. One of the results of the increased use of mathematics, especially arithmetic, was the invention of Babbage's calculating machine in 1822. The usefulness of this invention was so apparent that it was not long in coming into use, or long in causing the invention of improvements on it of many kinds. The calculating machine was a distinct contribution to civilization.