They were both typed on that Underwood Portable of yours .sx And the letter to Peter Thursford shows precisely the same defects .sx " Viola seemed dazed by this damning evidence .sx " I don't understand it , " she muttered .sx Then her coolness seemed to return again .sx " I never wrote either of these letters , " she said , keeping her voice firm by an obvious effort .sx " I don't understand what's been going on .sx But I never wrote anything even remotely like that kind of thing .sx I never wrote to Mr. Peter Thursford in my life , not a line .sx I haven't written to Mr. Falgate for months -years , I should say .sx " Severn was quite unimpressed .sx This was what he expected her to say , once she had begun to deny her authorship .sx She had to brazen the thing out now , even in the face of the facts .sx " I'd like to see your signature - no , don't bother to write it now , " he added as she picked up a pen from her desk .sx Obviously she would be on her guard and would write something slightly different from her normal signature .sx He thought for a moment or two before he hit on a fair test .sx " Have you any book with your name written on the fly-leaf ?sx " .sx She reflected for a moment .sx Severn guessed that she was calculating whether she could venture to risk the test .sx " A newish book , " he added quickly .sx People changed their signatures sometimes , and he did not want to give her the chance of producing an old book with an out-of-date signature in it .sx His glance ranged round the room and lighted on a tiny bookshelf .sx Walking over to it , he picked up bookafter book until he came to one in which her name was written , then another , and a third .sx " These will do , " he said .sx On the first fly-leaf he found V. Langdale which he compared with the signature of the letter to Peter Thursford .sx The second book had the inscription Viola Langdale and he compared the writing of the christian name with the signature on the letter to Falgate .sx The third book had Viola Langdale inscribed in it also , and again he made a minute comparison .sx So far as he could see , the signatures on the letters corresponded - as closely as any two signatures do correspond in practice - with these on the books .sx Without comment he showed the writings to Viola .sx " I don't care , " she said , obstinately .sx " I didn't either type or sign these letters .sx " She bit her lip , evidently in great perplexity .sx " I don't understand this , " she broke out at last .sx " Why should anyone want to make out that I wrote these things .sx It's beastly , suggesting the things that letter hints at !sx I've a right to know more than you've told me , Mr. Severn .sx Where did you get hold of these letters ?sx I simply can't make head or tail of all this .sx How did they fall into your hands ?sx " .sx " Yes , I expect you'd like to find out as much as you can .sx But you're not going to , " was the Inspector's mental comment .sx Aloud , he took a different line .sx " Let's drop these letters for a moment , Miss Lang-dale .sx I think I can clear the thing up quicker if you'll tell me your movements on the afternoon and evening of the day you left here .sx That may help to put me on the track .sx It's a serious thing , this kind of letter-writing ; and I'm anxious to lay my hands on the person who's responsible .sx " Partly by his words - though they were purposely non-committal - and partly by his tone , he seemed to .sx be enlisting her as a helper now , instead of treating her as under suspicion .sx To his satisfaction , she responded to the treatment .sx She seemed to have not the slightest objection to giving him any information he wanted .sx " Begin at the afternoon , you say ?sx Very well .sx I had lunch at the usual time .sx Then I took my maid and her suit-case down into the village in my little car .sx She was going to stay with friends there while I was away .sx I came back here , finished my packing , had some tea , washed up the tea-things , looked to all the window-catches , and then went off with my own suit-case in my car .sx " " What time would that be ?sx " Severn interposed .sx " Oh , about five o'clock or so .sx I didn't look at my watch .sx " " Where did you go ?sx " .sx " I was going to London .sx I drove on until about dinner-time , and then I had dinner at a small hotel on the road .sx I can't remember its name .sx " " No , I bet you can't , " was the Inspector's sardonic comment to himself .sx " I know that inn quite well .sx When you come to look for it , its address is The Back o' Beyond , on the Road to Nowhere and you never can remember anything about it afterwards .sx " But Viola's next words shattered his hopes .sx " When I got to London , I put up at the Enterkin Hotel near Hyde Park Gate , where I always stay when I'm in London .sx They know me there .sx I'd telegraphed for a room from a post office on the road .sx " " When did you get there ?sx " the Inspector asked with a last effort .sx " Oh , about half-past nine or so .sx " That finished it !sx If Viola was in London at 9.30 on the night that Peter Thursford was killed , she could not by any possibility have been on the spot , here , when he died .sx The Inspector could make a good guess at when peoplewere telling the truth ; and Viola's story certainly gave him the impression that it was accurate , now that she had come down to definite , checkable details .sx If she were lying , she would never have taken the risk of mentioning a particular hotel and saying that it was one where she was well known .sx That could be checked .sx And it would be checked , too .sx Severn would see to that .sx " What took you to London ?sx " he enquired casually .sx " I'm getting some dresses there , " Viola said curtly , as though the subject were displeasing in some way .sx " And I had to go up to get fitted sometime .sx I took the opportunity of going then .sx " " And you never heard of Mr. Peter Thursford's death ?sx " .sx " How could I ?sx " Viola demanded in a surprised tone .sx " I don't read newspapers when I'm in London .sx I've plenty of other things to do .sx And I'd left no address here , so no one wrote to me .sx Of course I didn't hear about it .sx And you're the first person I've seen - except my maid in passing - since I got back here .sx I think you'd better tell me what's happened now .sx " She paused abruptly , as though something had passed through her mind .sx " Oh , I begin to see !sx You thought I was mixed up in it because of those letters ?sx Is that it ?sx " .sx Severn took refuge in a short narrative of Peter Thursford's end .sx When he had finished , Viola was silent for a few moments .sx " I see , " she said slowly .sx " And these letters were found on Mr. Peter Thursford and Mr. Falgate ?sx That's very strange .sx Let me see the things again , please .sx " She examined them deliberately , both typescript and signatures , and then handed them back .sx " You're quite right .sx The typing is the same as my own machine's , and these signatures are exactly like .sx mine .sx But these letters weren't written by me , Mr. Severn .sx I never saw them until you took them out of your pocket .sx I can't imagine who's done this .sx " " Just one more question , " said Severn .sx " Why did you not leave your London address when you went there ?sx You knew where you were going even before you left here , I suppose .sx " Viola looked at him reflectively .sx Her coolness had come back to her again .sx " Is it essential that you should pry into my affairs ?sx Well , then , I went away from here because I was being pestered by somebody and I wanted to stop that .sx If I'd left my address , I might have been followed and bothered again .sx That's why .sx " Severn had no need to push his enquiry further .sx The maid had told him about Harry Thursford's persistence in coming to Azalea Cottage after the engagement had been broken off .sx Viola's whole story hung together perfectly with the other evidence which he had .sx He retired in good order ; but as he walked back to the police station , his feelings were anything but pleasant .sx In some ways that interview had been disastrous for his self-esteem .sx He had gone to it with the certainty that Viola Langdale held one of the keys of the mystery ; and now he was left puzzled as to her real position .sx Her story tallied perfectly well with all the other facts which he had about her movements ; and he was quite prepared to admit that investigation would probably confirm her statement that she was at a London hotel at the time Peter Thursford was killed .sx But that didn't mean she was entirely cleared .sx These letters might be genuine after all , in spite of her denials .sx She might not have been on the spot , but she might have acted as decoy to bring Peter Thursford to the place where he met his death .sx At the police station he got out his microscope and examined the signatures on the decoy letters ; and as he did so , he vented his feelings in a heart-felt oath .sx There , plain enough , he could see the work of the forger revealed :sx the hesitations of the pen , the wavering edges of the lines , even a faint retouching at one place where the first tracing had been unsatisfactory .sx What a fool he had been !sx Cocksure of the identity of the typewriter itself , he had neglected to put the signatures through the test .sx Just at the critical point he had given thoroughness the go-by , deserted his principles , and missed an essential fact in the case .sx Very much shaken in his confidence , he began to wonder if he had not made some mistake about the typewriting itself .sx Again he went over the documents :sx the letter to Falgate , the letter to Peter Thursford , his own impressions from the Underwood Portable , and Viola's copy taken at his dictation .sx It was with a sigh of relief that he put them down at last .sx No , he'd made no mistake there .sx The whole lot of them came from the one machine .sx And what was more , the blackness of the ribbon-impression was practically the same in them all , which showed that all of them had been written within the last few days .sx A final test occurred to him .sx This time he would be thorough in every detail .sx When these typescripts had begun to bulk largely in his case , he had gone to a public library and taken out Osborn's Questioned Documents to familiarise himself with the proper procedure in the identification of typewriters ; and now a case described in that book came back to his mind .sx Typewriter ribbons have their individual characteristics also .sx No two of them are woven exactly alike .sx Eagerly he set about his new test .sx Taking the letter to Falgate first , he put it under .sx his microscope and examined one of the capital " I's .sx " Magnified in this way , the line which to the naked eye seemed uniform was now revealed as a series of spots with very minute spaces between them , each spot corresponding to the impression of one of the horizontal threads of the ribbon .sx Where the type-face encountered the gaps between two adjacent threads , no impression had been left on the paper .sx Fortunately for the Inspector , the ribbon was a well-worn one , which made the test easier .sx Severn counted the dots in the stalk of the capital " I " and found thirteen of them , which showed that the ribbon had been woven of a texture containing thirteen threads in the height of a capital letter .sx Turning to the letter to Peter Thursford , he found thirteen threads there also , and the same number in his own impressions and in the copy which Viola had taken down under his dictation .sx " Well , that's clinched , " he assured himself in a more cheerful tone .sx " Same paper , same typewriter same ribbon :sx there's no doubt about that point , anyhow .sx " And now his interview with Viola Langdale appeared in a better guise .sx He had been on the wrong track at the start ; but none the less he had got the information he really needed to advance his case .sx He took out his table of alibis , changed the dash at Viola's name to a cross in the third column , and examined the result .sx