Learned and voluminous as were the purely literary productions of the Hispano-Arab scholars, they were of secondary importance when compared with the practical achievements of the experimenters in the world of science. The Saracens introduced into Western Europe the Indian numerals, the tabulated observations of Babylon, and the discoveries of the astronomers of the Alexandrian School. These wise investigators examined the effect of gravity, and narrowly missed ascertaining its principles; they constructed the pendulum clock and the balance; they explained with perspicuity and exactness the origin of many hitherto mysterious physical occurrences which popular ignorance was accustomed to ascribe to supernatural intervention rather than to the inexorable and necessary operation of Nature’s laws. They were the first to demonstrate that the aerolite was a cosmic fragment and not a missile of Divine wrath, and to subject the substances of which it was composed to chemical analysis. They formulated a table of specific gravities, and the densities of bodies as laid down by them is said by Tyndall not to vary essentially from those accepted at the present day. They understood the force of capillary attraction; they had approximated to the true height of the atmosphere, and had noted its diminished weight at a distance from the earth. As early as the tenth century they had formed singularly correct ideas of the nature and causes of many geological phenomena,--such as the varying erosion of strata by the action of the elements, the presence of fossil remains on the summits of mountain ranges and the different characteristics they exhibited according as their origin was terrestrial or aquatic, the elevation and depression of the surface of the globe extending through inconceivably protracted periods of time. Both chemistry and pharmacy were pursued with remarkable success in the laboratories of Moorish Spain. Medicine and surgery especially engaged the attention of the ambitious student, who found an enthusiastic and dangerous competitor for distinction in the Hebrew, whose attainments and skill not unfrequently placed him at the head of his profession. Dissection was not unknown, but reverence for the dead preserved the human form from the scalpel, and the anatomical researches of the Arab surgeon were, in public at least, limited to animals of the lower orders, multitudes of which were annually sacrificed to the demands of science. In that noble pursuit which has for its object the determination of the motions of the celestial bodies, and the establishment of their relations with each other and with the universe, the Hispano-Arab, as in the investigation of other natural phenomena and in the solution of abstruse philosophical problems, evinced a rare and peculiar aptitude. In Moorish Spain, as in Chaldea, Babylonia, and ancient Egypt--where all astronomers were priests--the sanctuary of God was in part devoted