Illustrated Companion to the Latin Dictionary/Umbilicus

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. 

UMBILI'CUS (ὀμφαλός). Literally, the navel; whence applied to other objects which have some external resemblance to the appearance of the navel, or to its position as the central part of the body; as —

1. The extreme end of the cylinder upon which an ancient book was rolled, and which, with the sheet folded round it, presents considerable resemblance to the human navel, as exhibited by the extremity on the left side of the annexed example (Umbilicus/1.1), representing a book half unrolled, from a painting at Herculaneum. Many writers consider that the umbilici and cornua were the same thing, only designated by different terms; but there is good reason for believing that they were not precisely so. When a sheet was completely filled with writing, a stick was attached to the end of the sheet, round which the entire length was rolled. In the MSS. found at Herculaneum, these sticks do not project beyond the edges of the sheet on either side, but have their extremities in the same plane with it, as represented by the illustration. In ordinary libraries, or for volumes intended to be placed in a capsa, where any addition to the length would have been inconvenient, it seems probable that the roll was complete in this state, with the exception of merely having the end of the stick painted (Mart. iii. 2. v. 6.), which suggested the resemblance to a navel, and accurately received the name of umbilicus. But persons who were particular about the ornamental appearance of their books, added bosses (bullae) to the ends of the stick, which projected beyond the roll on each side, like the bursting horns of a heifer, when the umbilici so adorned would receive the name of cornua. Thus the two terms may be considered to a certain extent, or in some senses, as convertible ones; especially where they are used figuratively to designate the end of a book (Hor. Epod. xiv. 6. Mart. iv. 91. xi. 107.), where the cylinder, whose extremities they formed, was affixed.

2. The pin or index in the centre of a sun-dial (Plin. H. N. vi. 39.); otherwise termed GNOMON, which see.

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  Umbilicus/1.1