s Park at such an hour. I may
add that it was only by the merest accident or good luck that I
fathomed it after all. I had no idea into what part of the building he
had gone, but, knowing that he was somewhere inside, I watched from
the shrubbery. In fact, I was still in the grounds when _you_
arrived!"

"Then it was you I saw on the tower!"

"Oh, no, it was not! I had thoroughly examined the tower on my
previous visit, and what I found there had puzzled me badly. In fact
it was not until your admirable withdrawal from Friar's Park to-night
that the horrible explanation dawned upon me ...and I realized that
the object of inviting Sir Marcus to Upper Crossleys was to 'remove'
him! The first plan failed, of course; he never came. He went back
again on duty to Russia, I believe--for a time. But when he
returned--a second was adopted, at the Red House. However--the
murder-machine erected in accordance with the earlier plan was still
there--"

"Where?" I cried in bewilderment.

"On the tower of Friar's Park! It was the appearance of _Damar Greefe_
on the platform of the tower, armed with binoculars, which awakened me
to the ghastly truth. The device, never used in the case of Sir
Marcus, was not to be wasted, but was to be employed to remove a
dangerous obstacle from the conspirator's path! I had left the car
near Crossleys, you see, and never in my life have I run as I ran
after you to-night!"

"But, Gatton, _what_ did you find on the tower--and what connection
exists between the tower and the explosion which occurred here
to-night?"

"This: a sort of small howitzer--I think of Krupp's manufacture, but
you would be better able to judge than I--is mounted on the platform
of the tower! I examined it, Mr. Addison, last night, and like a fool
concluded that it had been used at some time for a local celebration
and never dismounted! It was trained--as I remembered nearly too
late--and laid at a certain elevation in such a way that it was
evidently never meant to be moved. Yet at the time the significance of
this did not strike me. How the range was found so exactly we shall
probably never know; but the truth suddenly burst upon me as you made
off through the bushes and as Dr. Damar Greefe came out and began to
peer through his glasses--that it was mechanically set in such a
manner that it could drop a projectile into the window above the porch
of the Abbey Inn!"

"Good God! It's hardly credible!"

"It isn't, I admit