galleries were thoroughly secure； I placed Frederic Larsan at the
end of the 'off…turning' gallery； before the window which I had
found open and had reclosed。
〃'Under no consideration；' I said to him； 'must you stir from this
post till I call you。 The chances are even that the man； when he
is pursued； will return to this window and try to save himself that
way； for it is by that way he came in and made a way ready for his
flight。 You have a dangerous post。'
〃'What will be yours？' asked Fred。
〃'I shall spring into the room and knock him over for you。'
〃'Take my revolver；' said Fred； 'and I'll take your stick。'
'Thanks；' I said； 'You are a brave man。'
〃I accepted his offer。 I was going to be alone with the man in the
room writing and was really thankful to have the weapon。
〃I left Fred； having posted him at the window （No。 5 on the plan）；
and； with the greatest precaution； went towards Monsieur Stangerson's
apartment in the left wing of the chateau。 I found him with Daddy
Jacques； who had faithfully obeyed my directions； confining himself
to asking his master to dress as quickly as possible。 In a few
words I explained to Monsieur Stangerson what was passing。 He armed
himself with a revolver； followed me； and we were all three speedily
in the gallery。 Since I had seen the murderer seated at the desk
ten minutes had elapsed。 Monsieur Stangerson wished to spring upon
the assassin at once and kill him。 I made him understand that；
above all； he must not； in his desire to kill him； miss him。
〃When I had sworn to him that his daughter was not in the room；
and in no danger； he conquered his impatience and left me to direct
the operations。 I told them that they must come to me the moment
I called to them； or when I fired my revolver。 I then sent Daddy
Jacques to place himself before the window at the end of the 'right'
gallery。 （No。 2 on my plan。） I chose that position 'for Daddy
Jacques because I believed that the murderer； tracked； on leaving
the room； would run through the gallery towards the window which
he had left open； and； instantly seeing that it was guarded by
Larsan； would pursue his course along the 'right' gallery。 There
he would encounter Daddy Jacques； who would prevent his springing
out of the window into the park。 Under that window there was a sort
of buttress； while all the other windows in the galleries were at
such a height from the ground that it was almost impossible to jump
from them without breaking one's neck。 All the doors and windows；
including those of the lumber…room at the end of the 'right' gallery
… as I had rapidly assured myself … were strongly secured。
〃Having indicated to Daddy Jacques the post he was to occupy； and
having seen him take up his position； I placed Monsieur Stangerson
on the landing at the head of the stairs not far from the door of
his daughter's ante…room； rather than the boudoir； where the women
were； and the door of which must have been locked by Mademoiselle
Stangerson herself if； as I thought； she had taken refuge in the
boudoir for the purpose of avoiding the murderer who was coming
to see her。 In any case； he must return to the gallery where my
people were awaiting him at every possible exit。
〃On coming there； he would see on his left； Monsieur Stangerson； he
would turn to the right； towards the 'off…turning' gallery … the way
he had pre…arranged for flight； where； at the intersection of the
two galleries； he would see at once； as I have explained； on his
left； Frederic Larsan at the end of the 'off…turning' gallery； and
in front； Daddy Jacques； at the end of the 'right' gallery。 Monsieur
Stangerson and myself would arrive by way of the back of the chateau。
… He is ours！ … He can no longer escape us！ I was sure of that。
〃The plan I had formed seemed to me the best； the surest； and the
most simple。 It would； no doubt； have been simpler still； if we
had been able to place some one directly behind the door of
Mademoiselle's boudoir； which opened out of her bedchamber； and；
in that way； had been in a position to besiege the two doors of the
room in which the man was。 But we could not penetrate the boudoir
except by way of the drawing…room； the door of which had been
locked on the inside by Mademoiselle Stangerson。 But even if I had
had the free disposition of the boudoir； I should have held to the
plan I had formed； because any other plan of attack would have
separated us at the moment of the struggle with the man； while my
plan united us all for the attack； at a spot which I had selected
with almost mathematical precision； … the intersection of the two
galleries。
〃Having so placed my people； I again left the chateau； hurried to
my ladder； and； replacing it； climbed up； revolver in hand。
〃If there be any inclined to smile at my taking so many precautionary
measures； I refer them to the mystery of The Yellow Room； and to all
the proofs we have of the weird cunning of the murderer。 Further； if
there be some who think my observations needlessly minute at a moment
when they ought to be completely held by rapidity of movement and
decision of action； I reply that I have wished to report here； at
length and completely； all the details of a plan of attack conceived
so rapidly that it is only the slowness of my pen that gives an
appearance of slowness to the execution。 I have wished； by this
slowness and precision； to be certain that nothing should be omitted
from the conditions under which the strange phenomenon was produced；
which； until some natural explanation of it is forthcoming； seems to
me to prove； even better than the theories of Professor Stangerson；
the Dissociation of Matter … I will even say； the instantaneous
Dissociation of Matter。〃
Chapter XVI
Strange Phenomenon of the Dissociation of Matter
（EXTRACT FROM THE NOTE…BOOK OF JOSEPH ROULETABILLE； continued）
〃I am again at the window…sill；〃 continues Rouletabille； 〃and once
more I raise my head above it。 Through an opening in the curtains；
the arrangement of which has not been changed； I am ready to look；
anxious to note the position in which I am going to find the murderer；
… whether his back will still be turned towards me！ … whether he is
still seated at the desk writing！ But perhaps … perhaps … he is no
longer there！ … Yet how could he have fled？ … Was I not in possession
of his ladder？ I force myself to be cool。 I raise my head yet
higher。 I look … he is still there。 I see his monstrous back；
deformed by the shadow thrown by the candle。 He is no longer
writing now； and the candle is on the parquet； over which he is
bending … a position which serves my purpose。
〃I hold my breath。 I mount the ladder。 I am on the uppermost rung
of it； and with my left hand seize hold of the window…sill。 In this
moment of approaching success； I feel my heart beating wildly。 I
put my revolver between my teeth。 A quick spring； and I shall be
on the window…ledge。 But … the ladder！ I had been obliged to press
on it heavily； and my foot had scarcely left it； when I felt it
swaying beneath me。 It grated on the wall and fell。 But； already；
my knees were touching the window…sill； and； by a movement quick as
lightning； I got on to it。
〃But the murderer had been even quicker than I had been。 He had
heard the grating of the ladder on the wall； and I saw the monstrous
back of the man raise itself。 I saw his head。 Did I really see it？
… The candle on the parquet lit up his legs only。 Above the height
of the table the chamber was in darkness。 I saw a man with long
hair； a full beard； wild…looking eyes； a pale face； framed in large
whiskers； … as well as I could distinguish； and； as I think … red
in colour。 I did not know the face。 That was； in brief； the chief
sensation I received from that face in the dim half…light in which I
saw it。 I did not know it … or； at least； I did not recognise it。
〃Now for quick action！ It was indeed time for that； for as I was
about to place my legs through the window； the man had seen me； had
bounded to his feet； had sprung … as I foresaw he would … to the
door of the ante…chamber； had time to open it； and fled。 But I was
already behind him； revolver in hand； shouting 'Help！'
〃Like an arrow I crossed the room； but noticed a letter on the table
as I rushed。 I almost came up with the man in the ante…room； for he
had lost time in opening the door to the gallery。 I flew on wings；
and in the gallery was but a few feet behind him。 He had taken； as
I supposed he would； the gallery on his right； … that is to say； the
road he had prepared for his flight。 'Help； Jacques！ … help； Larsan！'
I cried。 He could not escape us！ I raised a shout of joy； of
savage victory。 The man reached the intersection of the two
galleries hardly two seconds before me for the meeting which I had
prepared … the fatal shock which must inevitably take place at that
spot！ We all rushed to the crossing…place … Monsieur Stangerson
and I coming from one end of the right gallery； Daddy Jacques coming
from the other end of the same gallery； and Frederic Larsan coming
from the 'off…turning' gallery。
〃The man was not there！
〃We looked at each other stupidly and with eyes terrified。 The man
had vanished like a ghost。 'Where is he … where is he？' we all
asked。
'It is impossible he can have escaped！' I cried； my terror mastered
by my anger。
〃'I touched him！' exclaimed Frederic Larsan。
〃'I felt his breath on my face！' cried Daddy Jacques。
〃'Where is he？' … where is he？' we all cried。
〃We raced like madmen along the two galleries； we visited doors and
windows … they were closed； hermetically closed。 They had not been
opened。 Besides； the opening of a door or window by this man whom
we were hunting； without our having perceived it； would have been
more inexplicable than his disappearance。
〃Where is he？ … where is he？ … He could not have got away by a
door or a window； nor by any other way。 He could not have passed
through our bodies！
〃I confess that； for the moment； I felt 'done for。' For the gallery
was perfectly lighted； and there was neither trap； nor secret door
in the walls； nor any sort of hiding…