They are _Macrobius_, _Delambre_, and _Conon_.

Come," he added, seeing Ardan hesitating and at a loss what other question to ask, "don't you want to know what lunar mountains are about the same height as the Peak of Teneriffe?
or as AEtna?
or as Mount Washington?
You need not be afraid of puzzling me.

I studied up the subject thoroughly, and therefore know all about it." "Oh! I could listen to you with delight all day long!" cried Ardan, enthusiastically, though with some embarrassment, for he felt a twinge of conscience in acting so falsely towards his beloved friend.

"The fact is," he went on, "such a rational conversation as the present, on such an absorbing subject, with such a perfect master--" "The Sun!" cried M'Nicholl starting up and cheering.

"He's cleared the disc completely, and he's now himself again! Long life to him! Hurrah!" "Hurrah!" cried the others quite as enthusiastically (Ardan did not seem a bit desirous to finish his sentence).
They tossed their maps aside and hastened to the window..