THE DOUBLE ALIBI 175 



probabl)' had carefully established an alibi of his 

 own elsewhere. 



The true account of Allen's appearance, or 

 apparition, at Blocksby's, when I and Tarras, 

 Wentworth and the attendant recognised him, and 

 Miss Breton did not, is thus part of the History 

 of the Unexplained. Allen might have appealed 

 to precedents in the annals of the Psychical 

 Society, where they exist in scores, and are 

 technicall}' styled ' collective hallucinations.' But 

 neither a jury, nor a judge, perhaps, would ac- 

 cept the testimony of experts in Psychical Re- 

 search if offered in a criminal trial, nor acquit a 

 wraith. 



Possibly this scepticism has never yet injured the 

 cause of an innocent man. Yet I know, in my own 

 personal experience, and have heard from others, 

 from men of age, sagacity, and acquaintance with 

 the greatest affairs, instances in which people have 

 been distinctl)' seen by sane, healthy, and honour- 

 able witnesses, in places and circumstances where 

 it was (as we say) ' physically impossible ' that 

 they should have been, and where they certainly 



