Oh, Barty was not patient most of the time, but this time it was smart, this time it was the better move, and this time it paid off. So did relocation on that note. A spell came bursting out of...no one visible, ho boy invisibility it was. But it wasn't headed toward where he currently was, and as soon as Barty knew that, he silently cast magical binding - rope stronger than muggle kind, harder to get out of - at the origin of the spell. Moving quickly again, Barty found another place, which gave him good access to the easiest ways out of the library - the lesser warded ones. This man was good at remembering where he had been, so Barty wasn't going to stay in one place dawdling.