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MISCELLANY
Geometry of the
Ideal Bee's Cell. The
bee's cell was the object of much discussion by amateur mathematicians
(and some who were more eminent) in the 18th and 19th centuries.
A good deal of nonsense
was written on the subject, for many of the writers did not realise
how seldom bees build cells conforming to the ideal pattern,
nor that the resulting cell-form depends much more upon the stresses
in the semi-plastic wax inside the warm building-cluster than
upon such considerations as an instinct for using the least amount
of wax possible. See B.W. 3, 37, for the history of the
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None of the investigators
seem, however, to have hit upon the interesting approximate solution
of the problem of "squaring the circle" provided by
the so-seldom-realised ideal cell. ABCD is one of the rhombs
or lozenges from the base of such a cell, AC and BD its diagonals,
meeting at O. Bisect the angle ABO by line BE. With BE as radius
and centre B, describe a circle, cutting AC at E. The square
on BD (or 2 x BO) is nearly equal to the area of this
circle. The proof is easy, recalling that BO, OA and AB are
in the proportions of the square roots of 1, 2 and 3 to one another;
while OB/BA, being the cosine of the angle ABO (or 2 x angle
EBO) is, by a well-known rule, equal to 2(OB/EB)2-1.
Now (2.OB/BE)2=(area of square PQRS divided by square of radius
BE)="pi," nearly. This, from the above, is = 2(OB/BA+1)
= 2(1/3 of the square root of 3+1)=2x1.57735=3.1547.
This is not a very close approximation, to "pi," being
about 4% out. But it is closer than the Egyptians' value, the
square of 16/9, or 3.1605. The accurate value, to 4 places of
decimals, is 3.1416; and the usual rough approximation 22/7,
is about 0.4% out.
A.D.B. |
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