remotely jocose out of them.  Then surely it was a concise order—­though a very strange one.  He was the last man in the world whose deliberate command I should care to disobey.  Possibly some chemical experiment was afoot; possibly——­Well, it was no business of mine to speculate upon why he wanted it.  I must get it.  There was nearly an hour before I should catch the train at Victoria.  I took a taxi, and having ascertained the address from the telephone book, I made for the Oxygen Tube Supply Company in Oxford Street.

As I alighted on the pavement at my destination, two youths emerged from the door of the establishment carrying an iron cylinder, which, with some trouble, they hoisted into a waiting motor-car.  An elderly man was at their heels scolding and directing in a creaky, sardonic voice.  He turned towards me.  There was no mistaking those austere features and that goatee beard.  It was my old cross-grained companion, Professor Summerlee.

“What!” he cried.  “Don’t tell me that you have had one of these preposterous telegrams for oxygen?”

I exhibited it.

“Well, well!  I have had one too, and, as you see, very much against the grain, I have acted upon it.  Our good friend is as impossible as ever.  The need for oxygen could not have been so urgent that he must desert the usual means of supply and encroach upon the time of those who are really busier than himself.  Why could he not order it direct?”

I could only suggest that he probably wanted it at once.

“Or thought he did, which is quite another matter.  But it is superfluous now for you to purchase any, since I have this considerable supply.”

“Still, for some reason he seems to wish that I should bring oxygen too.  It will be safer to do exactly what he tells me.”

Accordingly, in spite of many grumbles and remonstrances from Summerlee, I ordered an additional tube, which was placed with the other in his motor-car, for he had offered me a lift to Victoria.

I turned away to pay off my taxi, the driver of which was very cantankerous and abusive over his fare.  As I came back to Professor Summerlee, he was having a furious altercation with the men who had carried down the oxygen, his little white goat’s beard jerking with indignation.  One of the fellows called him, I remember, “a silly old bleached cockatoo,” which so enraged his chauffeur that he bounded out of his seat to take the part of his insulted master, and it was all we could do to prevent a riot in the street.

These little things may seem trivial to relate, and passed as mere incidents at the time.  It is only now, as I look back, that I see their relation to the whole story which I have to unfold.