Whether the flow and ebb are caused by the moon or the sun, or are
the breathing of this terrestrial machine. That the flow and ebb are
different in different countries and seas.

[Footnote: 1. Allusion may here be made to the mythological
explanation of the ebb and flow given in the Edda. Utgardloki says
to Thor (Gylfaginning 48): "When thou wert drinking out of the horn,
and it seemed to thee that it was slow in emptying a wonder befell,
which I should not have believed possible: the other end of the horn
lay in the sea, which thou sawest not; but when thou shalt go to the
sea, thou shalt see how much thou hast drunk out of it. And that men
now call the ebb tide."

Several passages in various manuscripts treat of the ebb and flow.
In collecting them I have been guided by the rule only to transcribe
those which named some particular spot.]