Neither Hevelius, nor Cassini, nor La Hire, nor Herschel, makes a single remark regarding their nature.
It was Schroeter, in 1789, who called the attention of scientists to them for the first time.

He had only 11 to show, but Lohrmann soon recorded 75 more.

Pastorff, Gruithuysen, and particularly Beer and Maedler were still more successful, but Julius Schmidt, the famous astronomer of Athens, has raised their number up to 425, and has even published their names in a catalogue.

But counting them is one thing, determining their nature is another.

They are not fortifications, certainly: and cannot be ancient beds of dried up rivers, for two very good and sufficient reasons: first, water, even under the most favorable circumstances on the Moon's surface, could have never ploughed up such vast channels; secondly, these chasms often traverse lofty craters through and through, like an immense railroad cutting.
At these details, Ardan's imagination became unusually excited and of course it was not without some result.