occurred to him that perhaps
beyond his range of vision there was a barricade of empty cases which
hid the door from the rest of the room.

He spent nearly three-quarters of an hour taking a bearing based upon
the problematical position of the lights, the height and density of the
box screen and then boldly and rapidly opened the door, stepped through
and closed it behind him. His calculations had been accurate. He found
himself in a room, the extent of which he could only conjecture. What,
however, interested him mostly was the accuracy of his calculation that
the door was hidden. An "L"-shaped stack of crates was piled within two
feet of the ceiling, and formed a little lobby to anybody entering the
vault the way Beale had come. They were stacked neatly and methodically,
and with the exception of two larger packing-cases which formed the
"corner stone" the barrier was made of a large number of small boxes
about ten inches square.

There was a small step-ladder, evidently used by the person whose
business it was to keep this stack in order. Beale lifted it
noiselessly, planted it against the corner and mounted cautiously.

He saw a large, broad chamber, its groined roof supported by six squat
stone pillars. Light came not only from mercurial lamps affixed to the
ceiling, but from others suspended above the three rows of benches
which ran the length of the room.

Mercurial lamps do not give a green light, as he knew, but a violet
light, and the green effect was produced by shades of something which
Beale thought was yellow silk, but which he afterwards discovered was
tinted mica.

At intervals along the benches sat white-clad figures, their faces
hidden behind rubber masks, their hands covered with gloves. In front of
each man was a small microscope under a glass shade, a pair of balances
and a rack filled with shallow porcelain trays. Evidently the work on
which they were engaged did not endanger their eyesight, for the
eye-pieces in the masks were innocent of protective covering, a
circumstance which added to the hideous animal-like appearance of the
men. They all looked alike in their uniform garb, but one figure alone
Beale recognized. There was no mistaking the stumpy form and the big
head of the Herr Professor, whose appearance in Oliva Cresswell's room
had so terrified that young lady.

He had expected to see him, for he knew that this old German,
poverty-stricken and ill-favoured, had been roped in by va