) was the name of the various instruments by means of
which the ancients measured the time of the day and night. The earliest and
simplest horologia of which mention is made, were called πόλος
their invention to the Babylonians, and Prof. Sayce says, “This is
perfectly correct;” Favorinus (ap. D. L.
; compare Suidas, s. v. Γνώμων
) to Anaximander, but this means only that he
was the first to set one up in Greece, at Sparta; and Pliny, probably by an
oversight (H. N.
2.187), to his disciple Anaximenes.
Herodotus mentions the πόλος
as two distinct instruments. Both,
however, divided the day into twelve equal parts, and were a kind of
sun-dial. The γνώμων,
which was also called
was the more simple of the
two, and probably the more ancient. It consisted of a staff or pillar
standing perpendicular, in a place exposed to the sun (σκιάθηρον
), so that the length of its shadow might be easily
ascertained. The shadow of the gnomon was measured by feet, which were
probably marked on the place where the shadow fell. (Hesych. sub voce
: Pollux, 1.72.) The gnomon is almost without
exception mentioned in connexion with the δεῖπνον
or the bath; and the time for the former was towards
sunset, or at the time when the shadow of the gnomon measured 10 or 12 feet.
(Aristoph. Eccl. 652
, with the
Schol.; Pollux, l.c.;
Menander, ap. Athen. 6.243
; Hesych. sub voce
) The longest shadow
of the gnomon, at sunrise and sunset, was 12 feet: it is only in jest that
Eubulus, ap. Athen. 1.8
118 Meineke), represents it as double the
length, where it is consulted by a very big man. The time for bathing was
when the gnomon threw a shadow of 6 feet. (Lucian, Cronos,
100.17; Somn. s. Gall.
later times the name “gnomon” was applied to any kind of
sun-dial, and especially to its finger, which threw the shadow, and thus
pointed to the hour. Even the clepsydra is sometimes called
“gnomon” (Athen. 2.42
The gnomon was evidently a very imperfect instrument, and it was impossible
to divide the day into twelve equal spaces by it. This may be the reason
that we find it only used for such purposes as are mentioned above. The
on the other hand, seems to have been a more
perfect kind of sun-dial; but it appears, nevertheless, not to have been
much used, as it is but seldom mentioned. (Aristoph. ap. Polluc. 9.46.) It
consisted of a basin [p. 1.973]
), in the middle of which the perpendicular staff or
) was erected, and in it the
twelve parts of the day were marked by lines. (Alciphron,
3.4; Lucian, Lexiph.
Another kind of horologium was the clepsydra
). It derived its name from
as in its original and simple form it consisted of a
vessel with several little openings (τρυπήματα
) at the bottom, through which the water contained in
it escaped, as it were, by stealth. This instrument seems at first to have
been used only for the purpose of measuring the time during which persons
were allowed to speak in the courts of justice at Athens. The time of its
invention or introduction is not known; but in the age of Aristophanes (see
93 and 857) it appears
to have been in common use. Its form and construction may be seen very
clearly from a passage of Aristotle (Problem.
clepsydra was a hollow globe, probably somewhat flat at the top part, where
it had a short neck (αὐλός
), like that of
a bottle, through which the water was poured into it. This opening might be
closed by a lid or stopper (πῶμα
prevent the water running out at the bottom. The clepsydra which Aristotle
had in view was probably not of glass or of any transparent material, but of
bronze or brass, so that it could not be seen in the clepsydra itself what
quantity of water had escaped. As the time for speaking in the Athenian
courts was thus measured by water, the orators frequently use the term
instead of the time allowed to
them (ἐν τῷ ἐμῷ ὕδατι,
p. 274.139; ἐὰν
ἐγχωρῇ τὸ ὕδωρ,
p. 1094.45). Aeschines (c. Ctesiph.
§ 197), when describing the order in which the several parties were
allowed to speak, says that the first water was given to the accuser, the
second to the accused, and the third to the judges. An especial officer
(ὁ ἐφ̓ ὕδωρ
) was appointed in the
courts for the purpose of watching the clepsydra, and stopping it when any
documents were read, whereby the speaker was interrupted; and it is to this
officer that Demosthenes calls out: σὺ δὲ ἐπίλαβε
i. p. 1103; § 8;
cf. c. Conon.
p. 1268.36, with Sandys' note). The time, and
consequently the quantity of water allowed to a speaker depended upon the
importance of the case; and we are informed that in a γραφὴ παραπρεσβείας
the water allowed to each party
amounted to eleven amphorae (Aeschin. de Fals. Leg.
§ 126), whereas in trials concerning the right of inheritance only
one amphora was allowed. (Demosth. c. Macart.
Those actions in which the time was thus measured to the speakers are called
by Pollux (8.113) δίκαι πρὸς ὕδωρ
others are termed δίκαι ἄνευ ὕδατος,
and in these the speakers were not tied down to a certain space of time. The
only instance of this kind of actions of which we know, is the γραφὴ κακώσεως
(Harpocrat. s. v. κάκωσις
The clepsydra used in the courts of justice however was, properly speaking,
no horologium; but smaller ones, made of glass, and of the same simple
structure, were undoubtedly used very early in families for the purposes of
ordinary life, and for dividing the day into twelve equal parts. In these
glass clepsydrae the division into twelve parts must have been visible,
either on the glass globe itself, or in the basin into which the water
flowed. These instruments, however, did not show the time quite correctly
all the year round: first, because the water ran out of the clepsydra
sometimes quicker and sometimes slower, according to the different
temperature of the water (Athen. 2.42
100.7); and secondly,
because the length of the hours varied in the different seasons of the year.
To remove the second of these defects the inside of the clepsydra was
covered with a coat of wax during the shorter days, and when they became
longer the wax was gradually taken away again. (Aen. Tact. 100.22.10.) Plato
is said to have used a νυκτερινὸν
in the shape of a large clepsydra, which indicated the
hours of the night, and seems to have been of a complicated structure.
.) This instance shows that at
an early period improvements were made on the old and simple clepsydra. But
all these improvements were excelled by the ingenious invention of
Ctesibius, a celebrated mathematician of Alexandria (about 135 B.C.). It is
called ὡρολόγιον ὑδραυλικόν,
described by Vitruvius (9.9
; compare Athen. l.c.
), and more fully by Galen (v. p. 82 K.): cf.
2.377 ff. Water was made to drop upon
wheels which were thereby turned. The regular movement of these wheels was
communicated to a small statue, which, gradually rising, pointed with a
little stick to the hours marked on a pillar which was attached to the
mechanism. It indicated the hours regularly throughout the year, but still
required to be often attended to and regulated. This complicated crepsydra
seems never to have come into general use, and was probably only found in
the houses of very wealthy persons. The sun-dial or gnomon, and a simpler
kind of clepsydra, on the other hand, were much used down to a very late
period. The twelve parts of the day were not designated by the name ὤρα
until the time of the Alexandrian
astronomers, and even then the old and vague divisions, described in the
were preferred in the
affairs of common life. At the time of the geographer Hipparchus, however
(about 150 B.C.), it seems to have been very common to reckon by hours.
(Comp. Becker-Göll, Charikles,
vol. i. p. 321 ff.)
There is still existing, though in ruins, a horological building, which is
one of the most interesting monuments at Athens. It is the structure
formerly called the Tower of the Winds,
but now known as the
Horological Monument of Andronicus Cyrrhestes.
expressly called horologium
by Varro (R.
3.5.17). This building is fully described by Vitruvius (1.6.4
), and the following woodcuts show its
elevation and ground-plan, as restored by Stuart.
The structure is octagonal; with its faces to the points of the compass. On
the N.E. and N.W. sides are distyle Corinthian porticoes, giving access to
the interior; and to the south wall is affixed a sort of turret, forming
three quarters of a circle, to contain the cistern which supplied water to
the clepsydra in the interior. On the summit of the building was a bronze
figure of a Triton, holding a wand in his hand; and this figure turned on a
pivot, so that the [p. 1.974]
wand always pointed above that
side of the building which faced the wind then blowing. The directions of
the several faces were indicated
Horological monument of Andronicus Cyrrhestes.
Ground-plan of the above.
by figures of the eight winds on the frieze of the entablature. On
the plain wall below the entablature of each face, lines are still visible,
which, with the gnomons that stood out above them, formed a series of
sun-dials. In the centre of the interior of the building was a clepsydra,
the remains of which are still visible, and are shown on the plan, where the
dark lines represent the channels for the water, which was supplied from the
turret on the south, and escaped by the hole in the centre. Three other
Athenian horologia are extant, one in the monument of Thrasyllus, another
that of Phaedrus in the British Museum (C. I. G
n. 522), a
third in the Theatre of Dionysus, besides others from different parts of
The first horologium with which the Romans became acquainted was a sun-dial
), and was, according to some writers, brought to
Rome by Papirius Cursor twelve years before the war with Pyrrhus, and placed
before the temple of Quirinus (Plin H. N.
7.213); Varro (cf.
Censorinus, de Die Nat.
23) stated that it was
brought to Rome from Catina in Sicily, at the time of the first Punic war,
by the Consul M. Valerius Messala, and erected on a column behind the
Rostra. But this solarium being made for a different latitude did not show
the time at Rome correctly. Ninety-nine years afterwards, the Censor Q.
Marcius Philippus erected by the side of the old solarium a new one, which
was more carefully regulated according to the latitude of Rome. But as
sun-dials, however perfect they might be, were useless when the sky was
cloudy, P. Scipio Nasica, in his censorship, 159 B.C., established a public clepsydra, which indicated the hours both
of day and night. This clepsydra was in after-times generally called
de Nat. Deor. 2.3. 4
, 87; Plin. Nat. 7.215
; Censorin. de Die Nat.
100.23.) The word hora
for hour was introduced at Rome at the time when the
Romans became acquainted with the Greek horologia, and was in this
signification well known at the time of Plautus (Pseudol.
1307). After the time of Scipio Nasica several horologia, chiefly solaria,
seem to have been erected in various public places at Rome. In a fragment of
ascribed by Ribbeck to Aquilius,
but by others to Plautus (cf. Ritschl, Parerg.
83 ff., 123
ff.), we have jam oppletum oppidumst solariis.
Cf. Ribbeck, Frag. Com.
p. 33. A magnificent horologium was
erected by Augustus in the Campus Martius. It was a gnomon in the shape of
an obelisk; but Pliny (Plin. Nat. 36.73
complains that in the course of time it had become incorrect. Another
horologium stood in the Circus Flaminius (Vitr.
). Sometimes solaria were attached
to the front side of temples and basilicas (Varro, L. L.
6.6). The old solarium which had been
erected behind the Rostra seems to have existed on that spot till a very
late period, and it would seem that the place was called ad Solarium,
so that Cicero uses this expression as
synonymous with Rostra or Forum (pro Quint.
18, 59; ad
4.10, 14). Horologia of various descriptions seem also
to have been commonly kept by private individuals (Cic. Fam. 16.1. 8
; Dig. 33
); and at the time of the emperors, the wealthy Romans used to
keep slaves whose special duty it was to announce the hours of the day to
their masters. (Juv. 10.216
, with Mayor's note;
; Petron. 26.)
From the number of solaria which have been discovered in modern times in
Italy (thirteen having been discovered in the neighbourhood of Rome alone),
we must infer that they were very generally used among the ancients. The
following woodcut represents one of the simplest horologia which have been
discovered; it seems to bear great similarity to that, the invention of
which Vitruvius ascribes to Berosus. It was discovered in 1741, on the hill
of Tusculum, and is described by Zuzzeri, in a work entitled D'una
antica villa scoperta sul dosso del Tusculo, e d'un
[p. 1.975]antico orologio a sole,
Venezia, 1746, and by G. H. Martini, in his Abhandlung von den
Sonnenuhren der Alten,
Leipzig, 1777, p. 49, &c.
Horologium. (From Tusculum.)
The following woodcut shows the same solarium as restored by Zuzzeri.
The same restored.
The breadth as well as the height (A O and P A) are somewhat more than 8
inches; and the length (A B) a little more than 16 inches. The surface (A O
R B) is horizontal. S P Q T is the basis of the solarium, which, originally,
was probably erected upon a pillar. Its side, A S T B, inclines somewhat
towards the basis. This inclination was called ἔγκλιμα,
or inclinatio solarii
and enclima succisum
), and shows the latitude or polar altitude of
the place for which the solarium was made. The angle of the enclima is about
40° 43′, which coincides with the latitude of Tusculum. In
the body of the solarium is the almost spherical excavation, H K D M I F N,
which forms a double hemicyclium (hemicyclium excavatum
Vitruv.). Within this excavation the eleven
hour-lines are marked which pass through three semicircles, H L N, K E F,
and D M J. The middle one, K E F, represents the equator, the two others the
tropic lines of winter and summer. The curve representing the summer tropic
is somewhat more than a semicircle, the other two curves somewhat smaller.
The ten middle parts or hours in each of the three curves are all equal to
one another; but the two extreme ones, though equal to each other, are by
one-fourth smaller than the rest. In the middle, G, of the curve D K H N I
J, there is a little square hole, in which the gnomon or pointer must have
been fixed, and a trace of it is still visible in the lead by means of which
it was fixed. It must have stood in a perpendicular position upon the
surface A B R O, and at a certain distance from the surface it must have
turned in a right angle above the spheric excavation, so that its end (C)
extended as far as the middle of the equator, as it is restored in the above
woodcut. Another solarium is described in G. H. Martini's Antiquorum
p. 93 f. (Lips. 1783); cf. Overbeck's
Clepsydrae were used by the Romans in their camps, chiefly for the purpose of
measuring accurately the four vigiliae into which the night was divided.
(Caes. de Bell. Gall.
5.13; Veget. de Re
3.8; Aen. Tact. 100.22.)
The custom of using clepsydrae as a check upon the speakers in the courts of
justice at Rome is said to have been introduced by a law of Cn. Pompeius, in
his third consulship (Tac. de clar. Orat.
38), who adds,
before that time the speakers had been under no restrictions, but spoke as
long as they deemed proper. But there is some inaccuracy here, as Cicero in
B.C. 70 (in Verr.
1.9, 25) speaks of his legitimae horae;
in B.C. 63 (pro Rab. Perd.
6) his defence is limited to half an hour, and in B.C. 59 (pro
33, 82) six hours are allotted. At Rome, as at Athens, the
time allowed to the speakers depended upon the importance of the case. Pliny
(Plin. Ep. 2.11
) states that on one
important occasion he spoke for nearly five hours, ten large clepsydrae
having been granted to him by the judices, but the case was so important
that four others were added. (Compare Plin. Ep.
; Martial, 6.35
.) The law of Pompeius only limited the time during which the
accuser was allowed to speak to two hours, while the accused was allowed
three hours in the case of prosecutions de vi.
(Ascon. in Milon.
p. 37, ed. Orelli.) It is
clear from the case of Pliny and others that this restriction was not
observed on all occasions. In a case mentioned by Pliny (Plin. Ep. 4.9
), according to law (e lege
) the accuser had six hours, while the accused
had nine. An especial officer was at Rome as well as at Athens appointed to
stop the clepsydra during the time when documents were read. (Apul.
i. and ii.; compare Ernesti, de Solariis,
in his Opuscul. Philolog. et
pp. 21-31; Wöpcke, Disquisitiones arch. math.
circa Solaria veterum,
Berol. 1842; Becker-Göll,
ii p. 407 ff.; and especially