… or possibly it was nervousness； … exclaimed： 〃And your own view
of the case？〃 〃I believe；〃 Maitland replied deliberately； 〃that
your father's death resulted from poison injected into the blood；
but this is a matter so easily settled that I prefer not to theorise
upon it。 There are several poisons which might have produced the
effects we have observed。 If； however； I am able to prove this
conjecture correct I have still only eliminated one of the three
hypotheses and resolved the matter to a choice between the suicide
and murder theories； yet that is something gained。 It is because I
believe it can be shown death did not result from natural causes
that I have so strongly urged Mr。 Browne not to leave the room。〃
〃Pardon me； sir！〃 ejaculated Browne； growing very dark and
threatening。 〃You mean to insinuate … 〃 〃Nothing；〃 continued
Maitland； finishing his sentence for him； and then quietly ignoring
the interruption。 〃As I have already said； I am somewhat familiar
with the usual methods of ferreting out crime。 As a lawyer； and
also as a chemical expert； I have listened to a great deal of
evidence in criminal cases； and in this and other ways； learned
the lines upon which detectives may confidently be expected to act；
when once they have set up an hypothesis。 The means by which they
arrive at their hypotheses occasionally surpass all understanding；
and we have； therefore； no assurance as to the view they will take
of this case。 The first thing they will do will be to make what
they will call a 'thorough examination' of the premises； but a
study of chemistry gives to the word 'thorough' a significance of
which they have no conception。 It is to shorten this examination
as much as possible； … to prevent it from being more tiresome to
you than is absolutely necessary；〃 he said to Gwen； 〃that I have
taken the liberty of ascertaining and recording most of the data
the officers will require。〃
〃Believe me；〃 Gwen said to him in an undertone not intended for the
rest of us； though we heard it； 〃I am duly grateful for your
consideration and shall find a fitting time to thank you。〃
With no other reply than a deprecating gesture； Maitland continued：
〃Now let us look at the matter from the standpoint of the officers。
〃They must first determine in their own minds how Mr。 Darrow met his
death。 This will constitute the basis of their first hypothesis。
I say 'first' because they are liable to change it at any moment it
seems to them untenable。 If they conclude that death resulted from
natural causes； I shall doubtless be able to induce them to waive
that view of the case until I have been given time to prove it
untenable … if I can … and to act for the present upon one of the
other two possible theories。 It appears； from our present
knowledge of the case； that； whichever one of these they choose；
the same difficulty will confront them。〃
Gwen looked at him inquiringly and he continued； answering the
question in her eyes：
〃This is what I mean。 Your father； whether he committed suicide
or was murdered； in all probability met his death through that
almost imperceptible wound under his chin。 This wound； so far as
I have yet been able to examine it without a glass； was made with
a somewhat blunt instrument； able； apparently； to little more than
puncture the skin and draw a drop or so of blood。 Of course； on
such a theory； death must have resulted from poisoning。 The
essential point is： Where is the instrument that inflicted the
wound？〃
〃Might it not be buried in the flesh？〃 Gwen asked。
〃Possibly； but as I have not been able to find it I cannot believe
it very likely； though closer search may reveal it；〃 replied
Maitland。 〃Your father's right forefinger；〃 he continued； 〃is
slightly stained with blood； but the wound is of a nature which
could not have been caused by a finger nail previously poisoned。
Since we know he pressed his hand to his throat this blood…stain
makes no more strongly toward the truth of the suicide theory than
it does toward that of the murder hypothesis。 Suppose now； for we
must look at all sides of the question； the officers begin to act
upon the assumption that murder has been committed。 What will
they then do？ They will satisfy themselves that the east window
was opened six and three…quarters inches and securely fastened in
that position； that the two south windows were closed and fastened
and that the blinds thereof were also closed。 They will ascertain
the time when death occurred； … we can easily tell them； … and this
will show them that neither of the blinds on the south side could
have been opened without so increasing the light in the room as to
be sure to attract our attention。 They will learn also that the
folding doors were locked； as they are now； on this side and that
these two gentlemen ＇indicating Browne and Herne＇ sat against them。
They will then turn to the hall door as the only possible means of
entrance and I shall tell them that the Doctor and I sat directly
in front of this door and between it and Mr。 Darrow。 I have taken
the liberty to cut the carpet to mark the positions of our chairs。
In view of all these facts what must they conclude？ Simply this：
no one entered the room； did the deed； and then left it； at least
not without being observed。〃 〃But surely；〃 I ventured to suggest；
〃you do not think they will presume to question the testimony of
all of us that no one was observed。〃
〃That is all negative evidence；〃 he replied； 〃and does not
conclusively prove that another might not have observed what we
failed to detect。 However； it is all so self…evident that they
will not question it。 I know so well their methods of reasoning
that I am already prepared to refute their conclusions at every
point； without； I regret to say； being myself able to solve the
mystery； though I may say in passing that I purposely am refraining
from formulating any theory whatever until I have ascertained
everything which it is possible to learn in the matter。 In this way
I hope to avoid the error into which the detective is so prone to
fall。 Once you set up an hypothesis you unconsciously； and in spite
of yourself； accentuate unduly the importance of all data making
toward that hypothesis； while； on the other hand you either utterly
neglect； misconstrue； or fail to fully appreciate； the evidence
oppugnant to your theory。 In chemical research I gather the material
for an entire series of experiments before performing any； so that
the first few shall not； either by satisfying or discouraging me；
cause me to leave the bush half beaten。
〃Let us see how； from the officers' standpoint； the murder hypothesis
now stands。 No assassin； it will be clear to them； could have
entered or left this room unobserved。 If； therefore； a man did enter
the room and kill our friend； we； all of us； must be his accomplices。〃
This remark drew some sort of exclamatory protest from every other
person in the room save Browne。
〃Ah； that is probably the true solution；〃 said the artist with
ill…concealed disgust。
This remark and the tone in which it was uttered would have been
discourteous under any circumstances； at this particular time and in
the painful situation in which we all found ourselves it was boorish
almost beyond endurance。
There was nothing in Maitland's manner to indicate that he had heard
Browne's remark； as he quietly continued：
〃You see this cold…blooded view； the mere statement of which causes
you all to shudder； … the more so because one of our number is the
daughter of the dead man； … is not to be entertained a moment and
is only mentioned to show the logical chain which will force the
officers into the certain conviction that no assassin did enter or
leave this room。 What； then； remains of their theory？ Two
possibilities。 First； the murderer may have done the deed without
entering。 If so； it is clear that he must have made use of the
partly…opened window。 This seems so likely that they will seize
upon it with avidity。 At first they will suggest that the assassin
reached in at the window and struck his victim as he sat by it。
This； they will urge； accounts for our not finding the weapon； and
they will be so sure that this is the correct solution of the
problem that I shall probably have to point out to them its patent
absurdity。 This illustrates the danger of forming an hypothesis
from imperfect data。 Remind them that Mr。 Darrow did not sit by
the window； but eight feet three and one…half inches from it； in
almost the exact centre of the room； and their theory falls to the
ground； only to be hastily replaced； as a drowning man catches at a
straw； by a slightly varied theory。 If the victim sat that distance
from the window； they will inform us； it is clear the murderous
implement must have been thrown or shot at him by the assassin。〃
〃Indeed；〃 said Mr。 Herne； 〃though I had not thought of that theory
it seems to me so plausible； now that you mention it； that I think
the officers will show rare acumen if they adopt it。 Very properly
may they hold that some projectile might have been shot through the
partly opened window and none of us have detected t