Shortly after Copernicus, came Johann Kepler, who was born in Württemburg in 1571, and died in 1630. He had been a pupil of Tycho Brahe, who did not succeed in making any great invention or discovery, but who did collect a great amount of data. Utilizing these, Kepler devoted many years to the study of Copernicus, and tried to invent a system which would explain some facts of astronomy that the system of Copernicus did not explain, notably the non-uniform speed of the planets. The main result of his labors was the famous Kepler's Laws, which were "1. The orbits of the planets are ellipses having the sun at one focus. "2. The area swept over per hour by the radius joining sun and planet is the same in all parts of the planet's orbit. "3. The squares of the periodic times of the planets are proportional to the cubes of their mean distances from the sun." These three discoveries, enunciated in three interdependent, concrete laws, constituted an invention which, while it was merely an improvement on Copernicus's, was so great an improvement as almost to make the difference between impracticability and practicability. Without this improvement, astronomy would not be what it is, navigation would not be what it is, the regulation of time throughout the world would not be what it is, and the present highly intricate but smoothly running machine of civilization could not exist at all, except in a vastly inferior form. The machine of civilization is dependent for its successful operation on the good quality and correct design of every other part. So is every other machine; for instance, a steam-engine. The Copernican System was not recognized for more than a century. It was, in fact, definitely rejected, and people were subjected to punishment and even torture for declaring their belief in it. One of the amazing facts surrounding Copernicus's invention was that he carried on his observations with exceedingly crude appliances. _The telescope had not yet been invented._ Who invented the telescope is not definitely known; but it is probable that both the telescope and the microscope (compound microscope) were invented by Jansen, a humble spectacle-maker in Holland. Both inventions were made about the year 1590, and were of the highest order of merit from the three main points of view,--originality, completeness and usefulness. Few inventions more perfectly possessing the attributes of a great invention can be specified. The originality of the conception of each seems unquestionable; the beautiful completeness of the embodied form of each was such that only improvements in detail were needed afterward; and, as to their usefulness, can we even imagine modern civilization without them both?