In England two noteworthy attempts have been made within a century,
looking to a more satisfactory sequence and selection of propositions
than is found in Euclid. Each began with a list of propositions arranged
in proper sequence, and each was thereafter elaborated into a textbook.
Neither accomplished fully the purpose intended, but each was
instrumental in provoking healthy discussion and in improving the texts
from which geometry is studied.
The first of these attempts was made by Professor Augustus de Morgan,
under the auspices of the Society for the Diffusion of Useful Knowledge,
and it resulted in a textbook, including "plane, solid, and spherical"
geometry, in six books. According to De Morgan's plan, plane geometry
consisted of three books, the number of propositions being as follows:
Book I. Rectilinear figures 60
Book II. Ratio, proportion, applications 69
Book III. The circle 65
----
Total for plane geometry 194
Of the 194 propositions De Morgan selected 114 with their corollaries as
necessary for a beginner who is teaching himself.
In solid geometry the plan was as follows:
Book IV. Lines in different planes, solids
contained by planes 52
Book V. Cylinder, cone, sphere 25
Book VI. Figures on a sphere 42
----
Total for solid geometry 119
Of these 119 propositions De Morgan selected 76 with their corollaries
as necessary for a beginner, thus making 190 necessary propositions out
of 305 desirable ones, besides the corollaries in plane and solid
geometry. In other words, of the desirable propositions he considered
that about two thirds are absolutely necessary.
It is interesting to note, however, that he summed up the results of his
labors by saying:
It will be found that the course just laid down, excepting the
sixth book of it only, is not of much greater extent, nor very
different in point of matter from that of Euclid, whose
"Elements" have at all times been justly esteemed a model not
only of easy and progressive instruction in geometry, but of
accuracy and perspicuity in reasoning.
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