43 Moreover, if any one alleges that it was not the third hour when the Jews cried out for the first time in the terms referred to, he simply displays himself most insanely to be an enemy to the Gospel; unless perchance he can prove himself able to produce some new solution of the problem. For he cannot possibly establish the position that it was not the third hour at the period alluded to. And, consequently, we surely ought rather to credit a veracious evangelist than the contentious suspicions of men.
But you may ask, How can you prove that it was the third hour? I answer, Because I believe the evangelists; and if you also believe them, show me how the Lord can have been crucified both at the sixth hour and at the third. For, to make a frank acknowledgment, we cannot get over the statement of the sixth hour in John's narrative; and Mark records the third hour: and, therefore, if both of us accept the testimony of these writers, show me any other way in which both these notes of time can be taken as literally correct.
If you can do so, I shall most cheerfully acquiesce. For what I prize is not my own opinion, but the truth of the Gospel. And I could wish, indeed, that more methods of clearing up this problem might be discovered by others. Until that be done, however, join me, if it please you, in taking advantage of the solution which I have propounded. For if no explanation can be found, this one will suffice of itself. But if another can be devised, when it is unfolded, we shall make our choice. Only don't consider it an inevitable conclusion that any one of all the four evangelists has stated what is false, or has fallen into error in a position of authority at once so elevated and so holy.
Source: The Harmony of the Gospels (New Advent)