“The device whereby I secure this at such a distance is an invention of my own which, for patent reasons—­I might almost say ’patent patent reasons’—­I will ask you to kindly keep to yourself.  To the diaphragm there I fasten this bit of burnished silver.  Upon this I concentrate a pencil of light which, when reflected, acts photographically upon a sensitised moving tape in this little box, and perfectly registers the minutest movement of the receiving diaphragm.  How I develop, etch, and reproduce this record, and transform it into a record of the ordinary type, you will see in due time—­and will kindly keep secret for the present.  You had better go now and send me the things on this list, as soon as possible,” and he passed me a paper, continuing: 

“We will not despair yet.  Our clever rival may not be ready to prove his case so quickly as we.  At all events, when he comes again I shall be in a condition to ascertain how far he has progressed.  I have some things I must settle before I can ask for an arrest, and I am not at all sure that M. Godin is in any better condition in this regard than I am.  By Jove!  I’d give something to know how that wizard has gotten so far without so much as a single sign to indicate that he had even moved in the matter.  I say, Doc, it beats me, blessed if it doesn’t!  Please say to Miss Darrow that I am at work upon a promising clue-promising for someone, anyway—­and may not see her for some time yet.”

I did as he requested, and, if I am any judge of feminine indications, my message did not yield Gwen unmixed pleasure; still, she said nothing to warrant such a supposition on my part.  I visited Maitland every day to learn what he might wish me to bring him, and also to carry him his mail, for he had determined to remain constantly on the watch at his new quarters.

I have thus far, in the narration of these incidents been perfectly candid both as regards my friends and myself, and, therefore, that I may continue in like manner to the end, I shall suppress certain qualms which are urging me to silence, and confess myself guilty of some things of which you will, perhaps, think I may well be ashamed.  Be that as it may, you shall have the whole truth, however it may affect your opinion of me.  One reason why I went to Maitland’s new quarters so often, and stayed there so long, was because I was always permitted to relieve him of his watch.  With a telephone receiver strapped to my right ear, and my eyes fastened upon the screen of the camera obscura, I would sit by the hour prying into the affairs of the two people in the next room.  I tried for a number of days to ease my conscience by telling myself that I was labouring in the cause of justice, and was not a common eavesdropper.  This permitted me to retain a sort of quasi self-respect for a day or two till my honesty rallied itself, and forced me to realise and to admit that I was, to all intents and purposes,