We have digressed. Let us return to our theme. They toiled for science sake, not for fame. They looked for none. When Spain itself, indebted to them for all her blessings, repays so miserably their faithful services, why should they look to Europe for recognition? "High minds," it has been truly said, "are as little affected by such unworthy returns for services, as the sun is by those fogs which the earth throws up between herself and his light."[24] [24] T. Moore's "Life of Sheridan," Vol. 2 Chap. iv. And so, expecting no thanks, and working for none, they advanced, with their present achievements as stepping stones, to the study of astronomy. And marvelous, almost incredible, is their success in this department. They determine the altitude of celestial bodies by means of the astrolabe. They register all the stars in their heaven, giving to those of the first magnitudes the names they still bear on our celestial maps and globes, writing thus indelibly their impress upon the celestial heaven, though it be denied them in the literature of Europe. They give us the words "azimuth," "zenith," "nadir," "almanac," and others. They compute time by the oscillations of the pendulum, and determine the true length of the year. They discover the theory of the refraction of light and ascertain the curvilinear path of a ray of light through the air. They explain the horizontal sun and moon, and why we see those bodies before they have risen and after they have set. They measure the height of the atmosphere and determine it to be nearly fifty-eight and one half miles. They give the true theory of the twilight, and of the twinkling of the stars. They not only know the spheroidal form of the earth, but approximately its diameter and circumference. Averroes discovers the spots upon the sun. Kepler alludes honorably to the observations of Levi ben Gerson, and Copernicus to those of Profiat Duran, and Laplace accepts Ibn Musa's proof of the diminution of the eccentricity of the earth's orbit, and Ibn Junis' proof of the obliquity of the ecliptic. They invent the first pendulum clock. They build the first observatory in Europe, the Giralda, (1196 A. C.) turned into a belfry after the expulsion of the Moors and Jews. They almost discover the laws of gravity, considering it terrestrial, reserving it for Newton to teach that it is universal. Rabbi Isaac ben Sid prepares for Alphonso X., king of Castile, new astronomical tables, for which Alphonso takes the credit, names them the Alphonsine tables, and is modest enough to remark: "That if God had called him (the king) into His councils when He created the universe, things would have been in a better and simpler order."