back upon the _ipsissima verba_ of the revelation made by the sailor's friend. Though in reality but an enunciation regarding the _authorship_ of certain chronometers, it might possibly enough appear, from its metonymic character, to be also a revelation regarding the _construction_ of chronometers. The sailor's error respecting the construction of chronometers is to be tested and exposed, not by any references to what his friend had said, but by the art of the chronometer maker. The demonstrable principles of the art, as practised by the makers of chronometers, must be the test of all supposed _revelations_ regarding the principles and mechanism of chronometer making. [Illustration: Fig. 114. THE GEOGRAPHY OF COSMAS.[33] (_From a reduced facsimile of the original print in the British Museum._)] Now, it will be found that those mistakes of the theologians to which I refer have been exactly similar to that of the navigator in the supposed case, and that they are mistakes which must be corrected on exactly the same principle. The departments in which the mistakes have been made, have, as in the false religious, been chiefly three,--the geographic, astronomic, and geologic provinces. The geographic errors are of comparatively ancient date. They belong mainly to the later patristic and earlier middle ages, when the monk Cosmas, as the geographer of the Church, represented the earth as a parallelogrammical plain, twice longer than it was broad, deeply indented by the inland seas,--the Mediterranean, the Caspian, the Red Sea, and the Persian Gulf,--and encompassed by a rectangular trench occupied by the oceans. Some of my audience will, however, remember that of the council of clergymen which met in Salamanca in 1486 to examine and test the views of Christopher Columbus, a considerable portion held it to be grossly heterodox to believe that by sailing westwards the eastern parts of the world could be reached. No one could entertain such a view without also believing that there were antipodes, and that the world was round, not flat,--errors denounced by not only great theologians of the golden age of ecclesiastical learning, such as Lactantius and St. Augustine, but also directly opposed, it was said, to the very letter of Scripture. "They observed," says Washington Irving, in his "Life of Columbus," "that in the Psalms the heavens are said to be extended like a hide,--that is, according to commentators, the curtain or covering of a tent, which among the ancient pastoral nations was formed of the hides of animals; and that St. Paul, in his Epistle to the Hebrews, compares the heavens to a tabernacle or tent extended over the earth, which they thence inferred must be flat." In the sectional view of Cosmas the heavens are represented as a semicircular vault or tent raised on perpendicular walls; a vast mountain beyond the "Great Sea," lofty as the innermost continent of the Buddhist cosmogony, rises immediately