A third map of the moon was executed in the seventeenth century by Dominique Cassini; superior to that of Riccioli in the execution, it is inexact in the measurements. Several smaller copies were published, but the plate long kept in the Imprimerie Nationale was sold by weight as old brass.
La Hire, a celebrated mathematician and designer, drew up a map of the moon four and a half yards high, which was never engraved.
After him, a German astronomer, Tobie Marger, about the middle of the eighteenth century, began the publication of a magnificent selenographic map, according to lunar measures, which he rigorously verified; but his death, which took place in 1762, prevented the termination of this beautiful work.
It was in 1830 that Messrs. Boeer and Moedler composed their celebrated Mappa Selenographica, according to an orthographical projection. This map reproduces the exact lunar disc, such as it appears, only the configurations of the mountains and plains are only correct in the central part; everywhere else—in the northern or southern portions, eastern or western—the configurations foreshortened cannot be compared with those of the centre. This topographical map, one yard high and divided into four parts, is a masterpiece of lunar chartography.
After these savants may be cited the selenographic reliefs of the German astronomer Julius Schmidt, the topographical works of Father Secchi, the magnificent sheets of the English amateur, Waren de la Rue, and lastly a map on orthographical projection of Messrs. Lecouturier and Chapuis, a fine model set up in 1860, of very correct design and clear outlines.
Such is the nomenclature of the different maps relating to the lunar world. Barbicane possessed two, that of Messrs. Boeer and Moedler and that of Messrs. Chapuis and Lecouturier. They were to make his work of observer easier.
They had excellent marine glasses specially constructed for this journey. They magnified objects a hundred times; they would therefore have reduced the distance between the earth and the moon to less than 1,000 leagues. But then at a distance which towards 3 a.m. did not exceed a hundred miles, and in a medium which no atmosphere obstructed, these instruments brought the lunar level to less than fifteen hundred metres.
CHAPTER XI.
IMAGINATION AND REALITY.
"Have you ever seen the moon?" a professor asked one of his pupils ironically.