Cuts on Wood
| Author | G. S. Sansom |
| DOI | 10.1177/0032258X3300600405 |
| Date | 01 October 1933 |
| Published date | 01 October 1933 |
| Subject Matter | Article |
Cuts on
Wood
HOW
THE
MICROSCOPE CAN
HELP
By G. S. SANSOM, D.Sc., F.R.M.S.
(On
behalf of the Surrey Constabulary)
DURIN G recent years the importance, in criminal cases, of
making a microscopical examination of firearms, cartridge
cases and bullets has been realized, and suitable comparison
microscopes have been designed to facilitate the work,
but
hitherto, few attempts have been made to compare the cut
surfaces of wood with the knife, or other instrument, employed
to produce the cuts.
Recently a number of experiments in this direction were
carried out with satisfactory results, and there is little doubt
that under favourable conditions the knife edge and cut surface
would show remarkable agreement and in certain cases afford
valuable evidence, which, though not visible to the naked eye,
could be recorded photographically.
One of the methods employed in the identification of fire-
arms and ammunition is based on the agreement of the marks
on the empty brass cartridge case with those on the striker and
breech block of the weapon. Now these marks are caused by
the impact of a hard metal surface with a softer one, and though
often slight, they are fairly constant and are durable; the
weapon and cartridge case can be kept indefinitely and the
comparison made at any time.
In
the casewe are considering, the identification marks on
the wood not only vary considerably
but
may in a few weeks
disappear owing to drying and shrinkage of the newly cut sur-
face.
In
addition to this, the knife edge is very delicate, com-
4°7
To continue reading
Request your trial