Last Night's Television: The Turn of the Screw, BB1; Three Men Go To Ireland, BBC2

The blunt verdict on BBC1's The Turn of the Screw is that Henry James's powerfully unsettling tale had been comprehensively vandalised. The qualification one would have to add is that the author himself might not entirely have disapproved. In the preface to the New York edition, after all, James made it clear that he didn't want mimsy, out-of-the-corner-of-the-eye-style ghosts – the sort of things that he found in the psychical research literature and which could easily be dismissed by the rationally minded as a mere trick of the light. "Good ghosts, speaking by the book, make poor subjects", he wrote, "and it was clear that from the first my hovering, prowling, blighting presences... would have to depart altogether from the rules. They would be agents in fact; there would be laid on them the dire duty of causing the situation to reek with an air of evil." Whatever legions of subsequent readers have thought, then, James seemed to happy to accept that Quint and Miss Jessel were really there and it was their job to make your flesh creep.

But James surely knew precisely what he was doing when he ensured that the evidence for the ghosts' existence is all hearsay, and never independently corroborated by a second witness. Indeed, there's a point in the story when the governess attempts to get someone else to see what she's seeing and fails. The terror of the story is a second-hand terror, even third-hand arguably, and that distance between perceived apparition and description is essential to its mood. Awkwardly for anyone adapting a work for cinema, film unavoidably makes eyewitnesses of us all, and neither Tim Fywell, the director, or Sandy Welch, the writer, had felt it necessary to find some visual equivalence for the careful ambiguity of the literary text. When the governess sees Quint on the tower for the first time so do we, and the thing that really haunts us as we read the story – uncertainty – vanishes to be replaced by a much duller kind of fretfulness, about when something is next going to pop out at us.

Whatever Henry James intended, The Turn of the Screw is a psychological case study or it is nothing, but by changing the frame so that it was a clinical case study, Welch effectively turned it into a rebuke against psychiatry, while at the same time ramping up a sense of the governess as a bundle of repressed sexual hysteria. Part of the DNA running through this adaptation was all those horror films in which a cocky young man of science has his certainties upturned, the instructee in this case being Dr Fisher, who even ended up seeing Quint himself, darting round a corner at the asylum. Add to this the decision to have one of the tweenies hurled off the roof shortly after muttering dark warnings at the governess and you should get some measure of how the terrifying indeterminacies of the original had been turned into a slightly shabby ghost-train ride.

Frankly, there was more empirical uncertainty about what exactly you were looking at in Three Men Go to Ireland, the latest instalment of an enterprise that began when the BBC invited Griff Rhys Jones, Rory McGrath and Dara O Briain to retrace the journey described in Jerome K Jerome's comic novel Three Men in a Boat. That proved successful, as did two follow-ups that also had an aquatic theme. The rationale for travelling by water is now beginning to wear distinctly thin through overuse, but that's never stopped the BBC when it thinks it's on a winning streak, so the trio have been sent off to cross Ireland by boat. They started with a working barge that advanced at just less than walking pace in front of a giant cloud of diesel smoke and then switched – for reasons of pure whimsy, one assumes – to an aquacar. Neither of these things providing a very successful armature for banter, they also included excursions to have a go at duelling in a Trinity College fencing society and to wander around a monastery built by Saint Fechin.

It's all perfectly harmless, I suppose, but you never quite know what the ratio of setup to serendipity is in the thing, only that there's a lot more of the former than they're quite owning up to. In Mullingar, the trio found themselves the guests of honour at a civic parade, complete with mayoral speech of welcome and a banner on the town square. But you couldn't suppress the suspicion that the BBC production team had had quite a bit to do with the organisation of this "surprise". I'm guessing that O Briain's deep reluctance to have either of his travelling companions do an Oirish accent is the real thing, and I think Griff Rhys Jones was genuinely cross when he couldn't start the barge's engine. Fortunately, his recent two-parter on anger seems to have done wonders for his ability to control his temper.