There is not a scratch on the roof of which he can make use.

Nothing has been allowed to go astray.

Then "one of his dogs"-- for he had boasted to his friend Ligur that he always went about with dogs to search out his game for him--suggested that some of the columns were out of the perpendicular.

Verres does not know what this means; but the dog explains.

All columns are, in fact, by strict measurement, more or less out of the perpendicular, as we are told that all eyes squint a little, though we do not see that they squint.