Lines, according to the usual course of the sun. An instantaneous motion of this kind would, in reality, be as difficult, as the retrogradation. But it might not strike the people so much. (Haydock)

Some take the lines to designate hours. But the sun is never up twenty hours in that country; and it must have been at such a height, as that it might appear visibly to recede, or to go forward, ten lines. We may therefore suppose, that they consisted only of half hours, (Tirinus) or less. (Calmet)

If the retrograde motion were instantaneous, as Cajetan believes, the day would only be five hours longer than usual; (Menochius) but if otherwise, it would be ten; as the sun would occupy five hours in going back, and as many to regain its former station. (Tirinus)

Usher supposes that the night was as much shortened, that so astronomical observations may still be verified without any confusion. But that would introduce a fresh miracle. Some assert that only the shadow went back, without any derangement in the heavenly bodies. Spinosa laughs at the ignorance of those people, who mistook the effects of a parhelion for a miracle. This author may boast of his superior knowledge. But how came the sages of Babylon (ver. 12.) to be unacquainted with such a natural cause? How came it so opportunely (Calmet) at the time appointed by the prophet? What improbable explanations are not those forced to admit, who deny to the Almighty the power of changing his own works! (Haydock)

The silence of profane historians respecting this miracle, is of little consequence. Herodotus (ii. 142.) seems to hint at it, as well as at that under Josue; (x.) being informed “by the Egyptians, that during 10340 years, the sun had risen four times in an extraordinary manner. It had risen twice where it ought naturally to set, and had set as often where it should rise.” He might have said more simply, that the sun had twice gone back. See Solin, 45. (Calmet)

St. Dion. Areop. ep. 7. ad Polycarp.

This last author thinks that this day was twenty hours longer than usual, supposing that the lines designate so many hours, and that the sun kept going back for ten hours. (Worthington)