There is sometimes some confusion over cell size(internal diameter) and
cell pitch (distance from mid wall to mid wall). Internal cell size
can't easily be determined from cell pitch due to variations in wall
thickness (with age?) Cell pitch is often quoted in a different format
i.e. number of cells per square inch  or square  centimetre.

For interest the following is data from some random measurements I took
from various frames:

1) 3 year old brood comb (drawn on untraceable foundation but probably
Steele & Brodie of UK)
Horizontal pitch 5.35mm(0.21") (Measurement of 149.7mm over 28 cells)
Vertical pitch 4.51mm (0.18") (Measurement of 148.85mm over 33 cells)
This gives 4.15cells per square cm.. (26.75cells persquare inch )
Average cell diameter was 5.09mm (0.20") measured using GO/NO GO plug gages
Wall thickness (at thinnest point) was 0.26mm (0.010") measured using a
Digital caliper. The wall thickness towards the hexagonal corners was
much thicker, the cell internal shape  being almost round.

2)  6 Month old Brood comb (Foundation origin possibly Thorne of UK)

3.77 cells per sq. cm. (24.3 cells per sq.  inch).
Cell diameter 5,58mm (0.22")
Wall thickness at thinnest point 0.18mm (0.007")

3) Self Drawn super comb (heather honey) from starter strips

There was a wide variation in cell size varying from 5.35mm (0.21") at
the top of the frame to 6.9mm (0.27") at the bottom
Wall thickness at thinnest point 0.15mm (0.006").

My conclusions from the above are that internal cell size probably
reduces somewhat with time due to thickening of the walls and that the
wall thickness starts off rather thicker than I had been led to believe
(I had been told that wall thicknesses were less than 0.1mm (0.004").(my
meathod of measuring wall was to close the calipers gently until it
gripped the wall) The cell shape in the newer comb was less round (more
hexagonal) than on the old comb.The bees when left to draw their own
comb and when convinced it is for honey storage, economise on wax useage
by opting for large cells.

Measurement equipment -Miutoyo 150mm (6") digital caliper. Various
calibrated pins for use as go/no go plug gages.
Alan Riach
Bathgate, Edinburgh Scotland

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