Horologium

XII tabulis ortus tantum et occasus nominantur, post aliquot annos adiectus est et meridies, accenso consulum id pronuntiante, cum a curia inter Rostra et Graecostasin prospexisset solem; a columna Maenia ad carcerem inclinato sidere supremam pronuntiavit, sed hoc serenis tantum diebus, usque ad primum Punicum bellum. princeps solarium horologium statuisse ante XII annos quam cum Pyrro bellatum est ad aedem Quirini L. Papirius Cursor, cum eam dedicaret a patre suo votam, a Fabio Vestale proditur. sed neque facti horologii rationem vel artificem significat nec unde translatum sit aut apud quem scriptum id invenerit. M. Varro primum statutum in publico secundum Rostra in columna tradit bello Punico primo a M’. Valerio Messala cos. Catina capta in Sicilia, deportatum inde post XXX annos quam de Papiriano horologio traditur, anno urbis CCCCLXXXX. nec congruebant ad horas eius lineae, paruerunt tamen ei annis undecentum, donec Q. Marcius Philippus, qui cum L. Paulo fuit censor, diligentius ordinatum iuxta posuit, idque munus inter censoria opera gratissima acceptum est. etiam tum tamen nubilo incertae fuere horae usque ad proximum lustrum. tunc Scipio Nasica collega Laenati primus aqua divisit horas aeque noctium ac dierum idque horologium sub tecto dicavit anno urbis DXCV. tam diu populo Romano indiscreta lux fuit.
(Pliny the Elder, Nat. Hist. 7.212-215)

In the Twelve Tables only sunrise and sunset are specified; a few years later noon was also added, the consuls’ apparitor announcing it when from the Senate-house he saw the sun between the Beaks and the Greek Lodging. When the sun sloped from the Maenian Column to the Prison he announced the last hour, but this only on clear days, down to the First Punic War. We have it on the authority of Fabius Vestalis that the first sundial was erected 11 years before the war* with Pyrrhus at the Temple of Quirinus by Lucius Papirius Cursor when dedicating that temple, which had been vowed by his father; but Fabius does not indicate the principle of the sundial’s construction or the maker, nor where it was brought from or the name of the writer who is his authority for the statement. Marcus Varro records that the first public sundial was set up on a column along by the Beaks during the First Punic War after Catania in Sicily had been taken** by the consul Manius Valerius Messala, and that it was brought from Sicily thirty years later than the traditional date of Papirius’s sundial, B.C. 264. The lines of this sundial did not agree with the hours, but all the same they followed it for 99 years, till Quintus Marcius Philippus who was Censor with Lucius Paulus placed a more carefully designed one next to it, and this gift was received as one of the most welcome of the censor’s undertakings. Even then however the hours were uncertain in cloudy weather, until the next lustrum, when Scipio Nasica the colleague of Laenas instituted the first water-clock dividing the hours of the nights and the days equally, and dedicated this timepiece in a roofed building, B.C. 159. For so long a period the divisions of daylight had not been marked for the Roman public.

* Begun 281 B.C.
** 263 B.C.

(tr. William Henry Samuel Jones, with his notes)