The travelers being desirous of examing the moon carefully during their voyage, in order to facilitate their studies, they took with them Boeer and Moeller's excellent Mappa Selenographica, a masterpiece of patience and observation, which they hoped would enable them to identify those physical features in the moon, with which they were acquainted. This map reproduced with scrupulous fidelity the smallest details of the lunar surface which faces the earth; the mountains, valleys, craters, peaks, and ridges were all represented, with their exact dimensions, relative positions, and names; from the mountains Doerfel and Leibnitz on the eastern side of the disc, to the Marefrigoris of the North Pole.