This is a military Sketch Set that's
designed to be field portable. The set is an example of
Plane
Table Surveying. This method was the official way the
U.S.G.S.
made maps for many decades and is old enough that there are plenty
of
free books on line that describe the methods (see
Links
below). Most any good book on surveying will have a chapter
on
plane table work.
The typical setup is to level the table then orient it so the top
is
facing North (true is preferred, but magnetic will do if so
noted). Any device that allows sighting to a landscape
feature
(called an alidade) allows drawing a line from a point on the
paper
that's your current location through the feature. Note that
the
exact bearing of the board/paper is not too important since the
lines
to the features are correct in a relative sense.
If you have a way to determine the distance to the feature then it
can
be scaled and marked as a point on the paper. The method of
stadia can
be used
with a telescope that has the required reticule. This may be
either a
surveying
instrument or a rifle scope. A laser or optical
range finder
would
also be a modern way to get the distance to a distant object.
If you don't have a way to get the distance then each feature line
can
be labeled in pencil with the feature name. One of the
feature
lines is to (or from) the new table location. The distance
between the two table locations needs to be established so the new
location can be added to the paper as a point. Now sighting
the
same features as before and drawing a line to them from the new
point
of table location results in locating
each visible feature as a point at which time the construction
lines
can be erased.
Feb 2011 email from Brian Haren (Blog)
"As background, I am a retired Army Corps of Engineers officer and
spent
most of my time in the Topographic field managing surveying,
mapping
and terrain analysis (military geography) efforts around the
world.
I
am very familiar with the M1913 Sketch Set as it remained in our
MTOE
authorizations into the 1980s. In my assignments as unit
commander
I've probably inventoried a few dozen of these things as they were
part
of our equipment authorization. By the time I came on active
duty
(1979) the process of 'military sketching' was already obsolete,
but we
seemed to hang onto a lot of old equipment 'just in case'.
None of my surveyors could really tell me how we
could use this sketch set, and there was no manual (FM or TM)
that
described it's use. We'd set them up occasionally for
equipment
displays, but that was about it. I always thought they
were a
quaint
item, something interesting to set up and play with.
Well, fast forward to my post-retirement years and
my growing interest in Army Topographic history and equipment.
I
came
across a semi-complete Sketch Set on eBay earlier this year and
grabbed
it. When it was delivered I was surprised to see it was
virtually
unused. It was lacking a compass, hand level and a few
smaller
expendable items like pencils and erasers, but the plane table,
tripod
and case were in almost new condition.
This acquisition sparked my interest - just how was
this Sketch Set supposed to be used? Why did the Army
adopt it,
and
what was it used for? Surprisingly, I already had the
answer but
didn't realize it. Part of my collection is a library of
old Army
map
reading and land navigation manuals that go back as far as 1917.
Prior
to 1938, before the Army had established standardized
topographic map
production and distribution (through the Army Map Service), it
was the
individual unit's responsibility to acquire or create local maps
for
internal use. Army doctrine, as outlined in these pre-1938
manuals,
heavily emphasized military sketching. If you were a
battalion or
regimental commander and you were going to the field you would
ring up
your engineers or S2 section and have them prepare a route
sketch and a
field sketch of the area you were going to be operating in.
What
did
the Engineers or Intel Section use to prepare these sketches?
Yup, the
M1913 Sketch Set.
In 1938 it appears that the Army realized it needed
to separate the practice of field sketching from map reading and
land
navigation. Military field sketching was a specialized
skill that
required a lot of training and practice, but map reading and
land
navigation was something EVERY soldier would need to learn.
This
is
when the the famous FM 21-26 (Map Reading and Land Navigation)
series
of manuals got its start. In 1938 the Army published FM
21-35,
Sketching, This FM was already in my collection, but I
never paid
much
attention to it (I think I picked it up as part of a package
purchase
along with several other manuals). A few months ago I was
flipping
through the FM and was surprised to see that a lot of the
illustrations
were of the M1913 Sketch Set! I sat down and read the
manual
cover to
cover and realized that it's this FM that specifically describes
the
use of the M1913 sketch set. In fact, the manual is built
around
the
sketch set and its use.
As far as I cant tell, FM 21-35 is the only manual
the Army ever produced that is focused on military sketching,
and as
far as I can tell, the Army never updated this FM - the 1938
publication is the first and only dedicated Army treatise on the
subject. Sketching continued to be lightly discussed in
future
editions of FM 21-26, but never to the detail covered in FM
21-35.
Copies of FM 21-35 come up occasionally on eBay, if you'd
like to
get
a copy.
So, what looks like happened is that the Army kept
the M1913 sketch set in the inventory (and continued to
manufacture
them up through at least the mid-1900s), but never updated the
basic
manual. Without the manual the practice of military
sketching
became a
lost art."
By removing the plastic cover on the
broad's built-in compass and cleaning it with Optic Guard Anti-Fog
Optical Cleaner the electrostatic charge seems to have been
removed. Prior to applying the cleaner the compass needle
was
attracted to the plastic and was stuck.
[an error occurred while processing this directive] page created 21 Jan
2010.
