Illustrated Companion to the Latin Dictionary/Coelum

This article incorporates text from a publication now in the public domain: Rich, Anthony (1849). The illustrated companion to the Latin dictionary, and Greek lexicon. p. vi. OCLC 894670115. https://archive.org/details/illustratedcompa00rich. 

COEL'UM (οὐρανός). A soffit, or ceiling, of which word it contains the elements through the French ciel. (Vitruv. vii. 3. 3. Florus, iii. 5. 30. and coelo capitis, the nether part of the scull, Plin. H. N. xi. 49.) The earliest buildings were only covered by an outer roof (tectum), the inside of which served as the ceiling; but as that was found to be an insufficient protection against the changes of weather and temperature, an inner one was afterwards contrived, which constitued the coelum, and gave rise to an extra member in the entablature, denoted externally by the zophorus or frieze.