William David Ross and Michael Vickers
Abacus (ἄβαξ, ἀβάκιον), a counting-board, the usual aid to reckoning in antiquity. The Egyptians, Greeks, and Romans alike used a board with vertical columns, on which (working from right to left) units, tens, hundreds, or (where money was in question) e.g. ⅛ obols, ¼ obols, ½ obols, obols, drachmae, sums of 10, 100, 1,000 drachmae, and talents were inscribed. When an addition sum was done, the totals of the columns were carried to the left, as in our ordinary addition. The numbers might be marked in writing or by pebbles, counters, or pegs.
5th-cent. theories about sound fall into two groups. Most though not all non-Pythagorean Presocratics were concerned primarily with the process of hearing (see especially Theophr. Sens.; cf. also Hippocr. De victu 1. 8 and 15 on hearing and voice). The Pythagoreans opened a musical perspective, beginning from observed correspondences between pitch-relations and the relative lengths of pipes or strings. They showed that the correspondences hold quite generally, through demonstrations using other sound-sources (see e.g. DK 18. 12, 13; texts attributing ‘experiments’ to Pythagoras himself are unreliable). The resulting hypothesis that pitch itself is a quantitative variable prompted deeper enquiries, beginning in the 4th cent., into the physical nature of sound, its causes, transmission, and attributes, as well as the process of hearing.
The Greeks did not recognise acoustics as a separate science; the issues were studied in other contexts, mainly by philosophers interested in sense-perception, by biologists and medical writers, and above all by harmonic theorists.
In *Alexandria (1) and Constantinople. He wrote an extant medical encyclopaedia, called the Tetrabiblon from its division into four sections. Beginning with a summary of drug theory (see
J. T. Vallance
Agathinus (Claudius Agathinus) a Spartandoctor of the 1st cent. CE, associated with the medical sect of the *Pneumatists and by at least one ancient source with the establishment of an eclectic medical sect founded on Pneumatism with additional doctrines from medical Empiricism and *Methodism. He was a pupil of *Athenaeus (3) of Attaleia, and was linked with the Stoic philosopher L. *Annaeus Cornutus. He may have taught the physicians *Archigenes and *Herodotus (2). Fragments of his doctrines are reported by *Galen and *Oribasius, amongst others. He wrote influential works on pulsation (grudgingly praised by Galen, 8. 748 Kühn), on semi-tertian fevers, and on the use of hellebore; little is now known of their contents.
M. Stephen Spurr
Edward Courtney and R. A. Kaster
Albinus (2) writer on music, geometry, and dialectic, probably identical with Ceionius Rufius Albinus (PLRE 1 ‘Albinus’ 14), the consul of