Many measurements have to be made repeatedly on large
numbers of bees. These can be taken in a simple way with the aid
of specific tools.
The tomenta hair eyeglass...
has it's own built in measuring wire. This particular version was made
with materials that were to hand and is a little more robust than
others I have seen.
There are several parts... the eyeglass itself was made of bakelite and
had a 100 mm focal length, the
electrical connector came from my junk box and the copper wire was a
strand pulled from some thick cable I had lying around.
The left hand illustration shows the basic eyeglass
that I started with.
The electrical connector block shown right is
stripped down to obtain the brass centre piece and the screws.
A series of 1 mm diameter holes was
drilled in the side of the body (note the stagger in the bottom row
The end of some 1 mm copper wire was soldered to
the brass connector and the wire fed through the holes, soldering
each time the wire passed over the front of the brass block.
Even pulling the wire tight each time, the result was still a little
loose so a dollop of superglue was used to firm everything up.
The guage wire shown in the
illustration left is fitted into the bore of the connector and the
screws tightened to hold the wire so that the flattened measuring tip
is in focus.
The enlarged view shows how the wire is flattened
at the end. The flattening is achieved using a pair of pliers, not
the jaws themselves but the root nearest the pivot so that adequate
leverage is obtained. The tab so formed is measured using a micrometer
and the squeezing repeated until the tip is exactly 0.40 mm thick.
Note... Plenty of illumination is required.
There are two
modifications I will perform some time in the future:-
is to fit another connector on the opposite side the eyeglass body so
that another wire can be fitted to act as a stop so that my thumb is
in a repeatable position.
The spring removed from an old alarm
clock will be my second modification and this will be fitted so that
the curl of the spring holds the eyeglass in place in my eyesocket
(I have seen jewellers use this method in the past).
A further possible modification may be needed in future to correct
astigmatic component of my eyesight defects... This would entail
cutting a circular portion from an old plastic spectacle lens and
gluing it inside the body of the eyeglass.
This enables rapid assessment of Cubital index using the 35 mm
projection method. (click on thumbnail image for full size printable
This may look complex at first sight but it is
quite easy once you have done two or three.
When using the projector ensure that the axis of the lens is exactly
perpendicular to the wall both horizontally and vertically.
The diagram left was drawn from a BIBBA
The Herold Fan is held flat
on the wall so that vein "AB" is parallel to the "rungs" of the right
hand ladder. The exteme right side of this "ladder" should pass
through the centre of point "A". The line that forms the left of this
"ladder" should pass through point "B".
The line that then
point"C" then represents the Cubital Index. Joint "C" is a broad
traingle, the actual measuring point should be the centriod of this
I had some difficulty drawing the
full sized versions of the Herold fan... There were some minor errors
in the original printed sheet that
I have. I have corrected these and provided both left and right hand
versions which can be printed via your browser. There are still some
minor errors but they are very small (less than 0.17 mm). I have used
colour to aid those that are, like me, challenged in the eyesight
Can be used with the projection
method for discoidal shift measurement. (click on small image at right for full
size printable version)
Is the technical term for the
device that measures tongue length (or more precisely tongue