Radius
（
ῥάβδος).
1.
A pointed rod or wand, employed by professors of geometry, astronomy, or mathematics
for describing diagrams in sand, etc. (
Cic. Tusc. v.
23;
Verg. Ecl. iii. 40).
2.
（
ἀκτίς). A ray of light, usually repre
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Urania with Radius. (Pompeian painting.)
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sented by artists as a sharp pointed spike; whence
corona radiis
distincta (
Flor. iv. 2, 91), a crown ornamented with metal
spikes to imitate the rays of the sun.
3.
（
ἀκτίς, κνήμη). The spoke of a wheel (
Georg. ii. 444; Ovid,
Met. ii. 318); so termed because it radiates from the nave, like a ray
of light from a centre; hence
rota radiata (Varro,
R. R.
iii. 5.15), a wheel with spokes as contradistinguished from the solid wheel (
tympanum), which had none.
