He gave a height of 11,400 feet to the highest mountains, and brought down the average of different heights to little more than 2,400 feet.

But Herschel was mistaken too, and the observations of Schroeter, Louville, Halley, Nasmyth, Bianchini, Pastorff, Lohrman, Gruithuysen, and especially the patient studies of MM.

Boeer and Moedler, were necessary to definitely resolve the question.

Thanks to these _savants_, the elevation of the mountains of the moon is now perfectly known.

Boeer and Moedler measured 1,905 different elevations, of which six exceed 15,000 feet and twenty-two exceed 14,400 feet.