Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-06-05
SCIENCE WINNING WAR ON CRIME
BY SURER LABORATORY MEANS
Uncanny instruments OF Bu-
reau of Standards Achieve
MarVelS.
Or. Souder Describes Meth
DDS of Perfecting Clues
and Identification.
BY THOMAS r. HENRY.

The forger, the counterfeiter and the
murderer are destined to wage pro-
gressively losing battle against higher
mathematics and super microscopes as
the gumshoe man gives way to the lab
oratory specialist.
The scientific detective with his I'M
canny instruments no longer is purely
a creation of the fiction writer's imag-
ination, DR.. Wilmer Souder of the Blu
reau OF Standards. told the National
Conference on Weights and Measures
meeting at that institution today.
The perfect crime, he pointed out,
becomes increasingly impossible by the
mathematical laws of chance as more
effective laboratory methods of iden-
tiication are established. At present,
he said. there are few really qualified
experts and the reluctance of courts TO
accept evidence from pseudo scientific
detectives" is we'll founded.
The Bureau of Standards. DR. Souder
said, has taken up the problem of iden-
LITIGATION of written and typewriter
documents, signatures, guns and bullets
in an effort 10 establish standards. 1t
is prosaic work with none of the thrill
of the old man hunt about it. 1nstru-
mentS have been developed after years
of effort.
Typewriter Clues Found.
The most perfect OF typewriters. he
said. almost always leaves clues which
can be found under the microscope
The Surer source for identification"
he said. lies in the adjustments for
the type on the bars after the machine
has been assembled Some letters will
be placed high and some low in the
line, some will be rotated, and some
will make contact with one portion of
the face before the other portion hits
the paper. Inspectors usually reduce
these to apparent uniformity so far as
the naked eye is concerned.
But these variations are all suscept-
ible to precision measurements and it
usually will be found that from to 10
characteristics are sufficient to estab-
lish the identity of the machine which
produced the document. Probability
fractions rapidly reduce the probability
OF two machines existing which will
produce documents having all the
characteristics specified. The evidence
speaks from every line of the docu-
ment. Attempts at destroying these
beacon lights of evidence through mutt
lation are seldom successful. as to do
so would require perfect analysis of
all defects in the machine and facili-
ties for this type an analysis are
limited"
Some special types of instruments for
analysis OF typewriting have been de-
veloped. he said but much depends on
the skin of the user Most typewriting
experts have developed their own in
struments after spending years in the
study of specimens of typewriting to
a Tor f4Ia ~
piled to satisfy juries.
Disguise in Writing Futile.
Even the cleverest attempts to dis
guiSe handwriting are equally futile,
he said, when a really qualified man
takes up the work. Here the scientific
detective not only must have mastered
the art Of precision measurement, but
must have acquired by himself an art
which cannot be transmitted by in
struction. He must be able to differ
entiate minute differences in the style
Of script, the slope, size and relation of
parts of the letters, and the methods
Of handling the pen. The absence of
consistency and the glaring discrepen-
cieS in attempted disguise are readily
separated from the true handwriting
features characteristic of the individual,
he said. Although handwriting identi-
rules, DR.. Souder said he was convinced
that some experts in this field are really
competent.
The Bureau of Standards has been
concerned especially with identified ton
Of guns and bullets Evidence from
the measurements of guns, bullets and
shells" he said. "at present in many
instances have little weight in courts
of law except in their general confusion
NJ i,,ri -
reasonable doubt. This is largely due
to the amateurish and incomplete
methods pursued by many so-called eX-
pertS. Properly prepared data on guns
and bullets often are unique in the
conclusiveness of identif1cationS and
possess definite superiority over direct
visual evidence. The markings are
definite and cannot make false or pur-
jured statements There is no limit to
the time available for study. The
mental state of the observer need not
be confused as is so often the case in
visual observations of murders"
Bullet Betrays Gun.
The make of a gun. he said can
sometimes ne told from the gross
markings on the bullet. the groove
widths and the depths, diameters and
twist markings of the barrel all sus-
CtpClDlt 10 microscopic measurement
Rifling cutters do not have smooth
edges. These tools wear out with each
cut and small tooth-like projections
along the cutting edge produce a con-
stantly changing pattern in the barrel.
Bullets pressed against this surface will
take these markings and retain them
to remarkable degree even after the
penetration of relatively hard materials.
Rust spots and injuries to the inner
surface of the barrel produce additional
identification marks. Firing pin and
breech markings on shells are equally
positive when they are available.
An extremely precise instrument, the
comparison miscroscope, has been de-
veloped for identifying bullets, he said.
This SO reduces the possibility of error
that, in the hands of one able to use
the instrument, a mistake is almost i'm
possible. The work is complicated by
the deformities in bullets caused by
penetrating hard substances such as
bone. Two bullets fired from the same
gun will not compare exactly because
marks will be made rust cavities, bits
OF metal and powder, or fouling marks
which develop in the barrel between
two shots. The expert must learn how
| TO disregard these and focus his atten-
! ton on the sort of marks that do not
| change.
The weights and measures delegates