, a bluff, grey-bearded man,
speaking in his broad Hallamshire dialect; "we take good care of that.
Each workman only does a part, the whole of the process being only known
to myself. It wouldn't do for us to give Professor Emden forty thousand
pounds for the secret and then allow it to fall into foreign hands. The
Germans would, of course, give anything for it," he added. "Emden is a
patriotic Englishman even though he is very eccentric, and if he liked
he could have got almost anything he cared to ask from Krupp's."

"That's just the point," I said; and then, as we walked back to the
office, I explained my fears. But, like the Professor himself, he only
laughed them to scorn. So that evening I again returned to London filled
with anxiety and disappointment.

Just before eleven that same night I strolled past the house of Hermann
Hartmann, in Pont Street, vaguely wondering what I could do to prevent a
theft which must, I knew, shortly be committed. In all probability the
ingenious Hartmann already had a secret agent in Joynson's works, but
even if he had, he would certainly not be able to discover the secret.
I had quite satisfied myself upon that point.

No, the peril lay in the Professor himself--the strange old pig-headed
patriot.

Scarcely had I passed Hartmann's house, the exterior of which I knew so
well, when I heard the front door close and saw a man coming down the
steps. As he walked in my direction I halted beneath a lamp to light a
cigarette, and by so doing I obtained a glimpse of his face as he
passed.

He was a young, good-looking, smartly dressed man, with dark eyes and
hair and a rather sallow complexion. I put him down to be an Italian,
but I had never set eyes upon him before. No doubt he was one of
Hartmann's travelling agents--a man who went up and down England
visiting the fixed spies of Germany, or "letter-boxes," as they are
known in the bureau of secret police in Berlin--collecting their reports
and making payments for information or services rendered.

Knowing so much of the ways of the German secret agent, curiosity
prompted me to follow him. He strolled as far as the corner of Sloane
Street and Knightsbridge, and then boarded a motor-bus as far as
Piccadilly Circus. Thence he walked to the German beer-hall, the
Gambrinus, just off Coventry Street, where he joined a tall, thin,
grey-moustached man, an Italian like himself, who was seated awaiting
him. I idled across to a table close by