---
title: "On Architecture · De architectura"
author: "Vitruvius"
translator: "Morris Hicky Morgan"
languages: [la, en]
shelf: "Classical Latin"
section: 19 of 22
url: https://scriptura.si/works/vitruvius-on-architecture/19/
cite: "Vitruvius, tr. Morris Hicky Morgan, On Architecture · De architectura, section 19. Scriptura (scriptura.si), https://scriptura.si/works/vitruvius-on-architecture/19/"
---

# On Architecture · De architectura

*Vitruvius, tr. Morris Hicky Morgan*

The only architectural treatise to survive from antiquity: firmness, usefulness and beauty, temples and the proportions of the human body, water, sundials and machines.

> Latin: ed. Fritz Krohn, from the Perseus Digital Library (canonical-latinLit, phi1056.phi001, CC BY-SA 4.0).

> English: Morris Hicky Morgan, from the Perseus Digital Library (phi1056.phi001.perseus-eng2). Notes are not included.

> Rows follow the references the two texts share (books, chapters and sections), cut where both reach the end of a sentence.

## 19. Book IX · chapters 3–8

Source: https://scriptura.si/works/vitruvius-on-architecture/19/ · cite a paragraph as https://scriptura.si/works/vitruvius-on-architecture/19/#p-N

[¶0] 3.1. 1. THE sun, after entering the sign Aries and passing through one eighth of it, determines the vernal equinox. On reaching the tail of Taurus and the constellation of the Pleiades, from which the front half of Taurus projects, he advances into a space greater than half the firmament, moving toward the north. From Taurus he enters Gemini at the time of the rising of the Pleiades, and, getting higher above the earth, he increases the length of the days. Next, coming from Gemini into Cancer, which occupies the shortest space in heaven, and after traversing one eighth of it, he determines the summer solstice. Continuing on, he reaches the head and breast of Leo, portions which are reckoned as belonging to Cancer.

> Latin: 3.1. Namque cum arietis signum iniit et partem octavam pervagatur, perficit aequinoctium vernum. cum progreditur ad caudam tauri sidusque vergiliarum, e quibus eminet dimidia pars prior tauri, in maius spatium mundi quam dimidium procurrit procedens ad septentrionalem partem. e tauro cum ingreditur in geminos exorientibus vergiliis, magis crescit supra terram et auget spatia dierum. deinde ⟨e⟩ geminis cum iniit ad cancrum, qui brevissimum tenet caeli spatium, cum pervenit in partem octavam, perficit solstitiale tempus, et peragens pervenit ad caput et pectus leonis, quod eae partes cancro sunt attributae.

[¶1] 3.2. 2.After leaving the breast of Leo and the boundaries of, Cancer, the sun, traversing the rest of Leo, makes the days shorter, diminishing the size of his circuit, and returning to the same course that he had in Gemini. Next, crossing from Leo into Virgo, and advancing as far as the bosom of her garment, he still further shortens his circuit, making his course equal to what it was in Taurus. Advancing from Virgo by way of the bosom of her garment, which forms the first part of Libra, he determines the autumn equinox at the end of one eighth of Libra. Here his course is equal to what his circuit was in the sign Aries.

> Latin: 3.2. E pectore autem leonis et finibus cancri solis exitus percurrens reliquas partes leonis inminuit diei magnitudinem et circinationis reditque in geminorum aequalem cursum. tunc vero a leone transiens in virginem progrediensque ad sinum vestis eius contrahit circinationem et aequat ad eam, quam taurus habet, cursus rationem. e virgine autem progrediens per sinum, qui sinus librae partes habet primas, in librae parte VIII perficit aequinoctium autumnale; qui cursus aequat eam circinationem, quae fuerat in arietis signo.

[¶2] 3.3. 3. When the sun has entered Scorpio, at the time of the setting of the Pleiades, he begins to make the days shorter as he advances toward the south. From Scorpio he enters Sagittarius and, on reaching the thighs, his daily course is still further diminished. From the thighs of Sagittarius, which are reckoned as part of Capricornus, he reaches the end of the first eighth of the latter, where his course in heaven is shortest. Consequently, this season, from the shortness of the day, is called bruma or dies brumales. Crossing from Capricornus into Aquarius, he causes the days to increase to the length which they had when he was in Sagittarius. From Aquarius he enters Pisces at the time when Favonius begins to blow, and here his course is the same as in Scorpio. In this way the sun passes round through the signs, lengthening or shortening the days and hours at definite seasons. I shall next speak of the other constellations formed by arrangements of stars, and lying to the right and left of the belt of the signs, in the southern and northern portions of the firmament.

> Latin: 3.3. Scorpionem autem cum sol ingressus fuerit occidentibus vergiliis, minuit progrediens meridianas partes longitudines dierum. e scorpione cum percurrendo init in sagittarium ad femina eius, contractiorem diurnum pervolat cursum. cum autem incipit a feminibus sagittarii, quae pars est attributa capricorno, ad partem octavam, brevissimum caeli percurrit spatium. ex eo a brevitate diurna bruma ac dies brumales appellantur. e capricorno autem transiens in aquarium adauget et aequat sagittarii longitudine diei spatium. ab aquario cum ingressus est in pisces favonio flante, scorpionis comparat aequalem cursum. ita sol ea signa circum pervagando certis temporibus auget aut minuit dierum et horarum spatia. Nunc de ceteris sideribus, quae sunt dextra ac sinistra zonam signorum meridiana septentrionalique parte mundi stellis disposita figurataque, dicam.

[¶3] 4.1. 1. THE Great Bear, called in Greek ἄρκτος or ἑλικη, has her Warden behind her. Near him is the Virgin, on whose right shoulder rests a very bright star which we call Harbinger of the Vintage, and the Greeks προτρυγητής. But Spica in that constellation is brighter. Opposite there is another star, coloured, between the knees of the Bear Warden, dedicated there under the name of Arcturus.

> Latin: 4.1. Namque septentrio, quem Graeci nominant ἄρκτον sive ἑλίκην, habet post se conlocatum custodem. ab eo non longe conformata est virgo, cuius supra umerum dextrum lucidissima stella nititur, quam nostri provindemiatorem, Graeci προτρυγητήν vocant; candens autem magis spica eius est colorata. item alia contra est stella media genuorum custodis arcti: qui arcturus dicitur est ibi dedicatus.

[¶4] 4.2. 2. Opposite the head of the Bear, at an angle with the feet of the Twins, is the Charioteer, standing on the tip of the horn of the Bull; hence, one and the same star is found in the tip of the left horn of the Bull and in the right foot of the Charioteer. Supported on the hand of the Charioteer are the Kids, with the She-Goat at his left shoulder. Above the Bull and the Ram is Perseus, having at his right... with the Pleiades moving beneath, and at his left the head of the Ram. His right hand rests on the likeness of Cassiopea, and with his left he holds the Gorgon's head by its top over the Ram, laying it at the feet of Andromeda.

> Latin: 4.2. E regione capitis septentrionis transversus ad pedes geminorum auriga stat in summo cornu tauri—ita quae in summo cornu laevo est, aurigae pedis una tenet partem stella—et adplicantur aurigae manui haedi, capra laevo umero. tauri quidem et arietis insuper Perseus—dexterioribus subter currentis basem vergiliis, at sinisterioribus caput arietis—et manu dextra innitens Cassiepiae simulacro, laeva supra tauri tenet gorgoneum, ad summum caput subiciens Andromedae pedibus.

[¶5] 4.3. 3. Above Andromeda are the Fishes, one above her belly and the other above the backbone of the Horse. A very bright star terminates both the belly of the Horse and the head of Andromeda. Andromeda's right hand rests above the likeness of Cassiopea, and her left above the Northern Fish. The Waterman's head is above that of the Horse. The Horse's hoofs lie close to the Waterman's knees. Cassiopea is set apart in the midst. High above the He-Goat are the Eagle and the Dolphin, and near them is the Arrow. Farther on is the Bird, whose right wing grazes the head and sceptre of Cepheus, with its left resting over Cassiopea. Under the tail of the Bird lie the feet of the Horse.

> Latin: 4.3. Item pisces supra Andromedam ex aequis [ventris] ex aequisque sunt supra spinam equi, cuius ventris lucidissima stella finit ventrem equi et caput Andromedae. manus Andromedae dextra supra Cassiepiae simulacrum est constituta, laeva ⟨supra⟩ aquilonalem piscem. item aquarii supra equi caput est. equi ungulae attingunt aquarii ⟨e regione volucrem. inter Cepheum et Andromedae⟩ genua Cassiepia media est dedicata. capricorni supra in altitudinem aquila et delphinus. secundum eos est sagitta. ab ea autem ⟨non longe⟩ volucris, cuius pinna dextra Cephei manum attingit et sceptrum, laeva supra Cassiepiae innititur. sub avis cauda pedes equi sunt subiecti.

[¶6] 4.4. 4. Above the Archer, Scorpion, and Balance, is the Serpent, reaching to the Crown with the end of its snout. Next, the Serpent-holder grasps the Serpent about the middle in his hands, and with his left foot treads squarely on the foreparts of the Scorpion. A little way from the head of the Serpent-holder is the head of the so-called Kneeler. Their heads are the more readily to be distinguished as the stars which compose them are by no means dim.

> Latin: 4.4. Inde sagittarii, scorpionis, librae insuper serpens summo rostro coronam tangit. eum medium ophiuchos in manibus tenet serpentem, laevo pede calcans mediam frontem scorpionis. a parte ophiuchi capitis non longe positum est caput eius, qui dicitur nisus in genibus. eorum autem faciliores sunt capitum vertices ad cognoscendum, quod non obscuris stellis sunt conformati.

[¶7] 4.5. 5. The foot of the Kneeler rests on the temple of that Serpent which is entwined between the She-Bears (called Septentriones). The little Dolphin moves in front of the Horse. Opposite the bill of the Bird is the Lyre. The Crown is arranged between the shoulders of the Warden and the Kneeler. In the northern circle are the two She-Bears with their shoulder-blades confronting and their breasts turned away from one another. The Greeks call the Lesser Bear κυνόσουρα and the Greater ἑλίκη. Their heads face different ways, and their tails are shaped so that each is in front of the head of the other Bear; for the tails of both stick up over them.

> Latin: 4.5. Pes ingeniculati adit fulcitve capitis tempus serpentis, cuius per vipereos flexus minor arctorum, qui septentriones dicuntur, inplicatur. delphinum contra volucris rostro est proposita lyra. inter umeros custodis et geniculati corona est ordinata. in septentrionali vero circulo duae positae sunt arctoe scapularum ⟨e regione⟩ dorsis inter se compositae et pectoribus aversae. e quibus minor κυνόσουρα, maior ἑλίκη a Graecis appellatur. earumque capita inter se dispicientia sunt constituta, caudae capitibus earum adversae contra dispositae figurantur; utrarumque enim superando eminent.

[¶8] 4.6. 6. The Serpent is said to lie stretched out between their tails, and in it there is a star, called Polus, shining near the head of the Greater Bear. At the nearest point, the Serpent winds its head round, but is also flung in a fold round the head of the Lesser. Bear, and stretches out close to her feet. Here it twists back, making another fold, and, lifting itself up, bends its snout and right temple from the head of the Lesser Bear round towards the Greater. Above the tail of the Lesser Bear are the feet of Cepheus, and at this point, at the very top, are stars forming an equilateral triangle. There are a good many stars common to the Lesser Bear and to Cepheus. I have now mentioned the constellations which are arranged in the heaven to the right of the east, between the belt of the signs and the north. I shall next describe those that Nature has distributed to the left of the east and in the southern regions.

> Latin: 4.6. In summo per caudas earum [esse dicitur] item serpens est porrecta, e qua stella quae dicitur polus elucet contra caput maioris septentrionis; namque qua est proxume draconem, circum ⟨polum⟩ caput eius involvitur. ima vero circum cynosurae caput iniecta est flexu porrectaque proxime eius pedes. haec autem intorta replicataque se attollens reflectitur a capite minoris ad maiorem, circa rostrum et capitis tempus dextrum … item supra caudam minoris pedes sunt Cephei, ibique ad summum cacumen facientes stellae sunt trigonum paribus lateribus. insuper arietis signum septentrionis †autem minoris et Cassiepiae simulacri complures sunt stellae confusae. Quae sunt ad dextram orientis inter zonam signorum et septentrionum sidera in caelo disposita, dixi [esse]; nunc explicabo, quae ad sinistram orientis meridianisque partibus ab natura sunt distributa.

[¶9] 5.1. 1. FIRST under the He-Goat lies the Southern Fish, facing towards the tail of the Whale. The Censer is under the Scorpion's sting. The fore parts of the Centaur are next to the Balance and the Scorpion, and he holds in his hands the figure which astronomers call the Beast. Beneath the Virgin, Lion, and Crab is the twisted girdle formed by the Snake, extending over a whole line of stars, his snout raised near the Crab, supporting the Bowl with the middle of his body near the Lion, and bringing his tail, on which is the Raven, under and near the hand of the Virgin. The region above his shoulders is equally bright.

> Latin: 5.1. Primum sub capricorno subiectus piscis austrinus caudam prospiciens ceti. ab eo ad sagittarium locus est inanis. turibulum sub scorpionis aculeo. centauri priores partes proximae sunt librae et scorpioni. tenet in manibus simulacrum, id quod bestiam astrorum periti nominaverunt. virginem et leonem et cancrum anguis porrigens agmen stellarum intortus succingit, regione cancri erigens rostrum, ad leonem medioque corpore sustinens craterem ad manumque virginis caudam subiciens. in qua inest corvus; quae sunt autem supra scapulas, peraeque sunt lucentia ad anguis inferius ventris.

[¶10] 5.2. 2. Beneath the Snake's belly, at the tail, lies the Centaur. Near the Bowl and the Lion is the ship named Argo. Her bow is invisible, but her mast and the parts about the helm are in plain sight, the stern of the vessel joining the Dog at the tip of his tail. The Little Dog follows the Twins, and is opposite the Snake's head. The Greater Dog follows the Lesser. Orion lies aslant, under the Bull's hoof; in his left hand grasping his club, and raising the other toward the Twins.

> Latin: 5.2. sub caudam subiectus est centaurus. iuxta cratera et leonem navis est, quae nominatur Argo, cuius prora obscuratur, sed malus et quae sunt circa gubernacula eminentia videntur, ipsaque navicula et puppis per summam caudam cani iungitur. geminos autem minusculus canis sequitur contra anguis caput. maior item sequitur minorem. Orion vero transversus est subiectus, pressus ungula tauri, manu laeva ⟨pellem⟩ tenens, clavam altera ad geminos tollens.

[¶11] 5.3. 3. At his feet is the Dog, following a little behind the Hare. The Whale lies under the Ram and the Fishes, and from his mane there is a slight sprinkling of stars, called in Greek ἁρπεδόναι, regularly disposed towards each of the Fishes. This ligature by which they hang is carried a great way inwards, but reaches out to the top of the mane of the Whale. The River, formed of stars, flows from a source at the left foot of Orion. But the Water, said to pour from the Waterman, flows between the head of the Southern Fish and the tail of the Whale.

> Latin: 5.3. Apud eius vero basim canis parvo intervallo insequens leporem. arieti et piscibus cetus est subiectus, a cuius crista ordinate utrisque piscibus disposita est tenuis fusio stellarum, quae graece vocitantur ἁρπεδόναι. magnoque intervallo introrsus pressus nodus serentium attingit summam ceti cristam [esse fuit]. per speciem stellarum flumen profluit, initium fontis capiens a laevo pede Orionis. quae vero ab aquario fundi memoratur aqua, profluit inter piscis austrini caput et caudam ceti.

[¶12] 5.4. 4. These constellations, whose outlines and shapes in the heavens were designed by Nature and the divine intelligence, I have described according to the view of the natural philosopher Democritus, but only those whose risings and settings we can observe and see with our own eyes. Just as the Bears turn round the pivot of the axis without ever setting or sinking under the earth, there are likewise stars that keep turning round the southern pivot, which on account of the inclination of the firmament lies always under the earth, and, being hidden there, they never rise and emerge above the earth. Consequently, the figures which they form are unknown to us on account of the interposition of the earth. The star Canopus proves this. It is unknown to our vicinity; but we have reports of it from merchants who have been to the most distant part of Egypt, and to regions bordering on the uttermost boundaries of the earth.

> Latin: 5.4. Quae figurata conformataque sunt siderum in mundo simulacra, natura divinaque mente designata, ut Democrito physico placuit, exposui, sed tantum ea, quorum ortus et occasus possumus animadvertere et oculis contueri. namque uti septentriones circum axis cardinem versantes non occidunt neque sub terram subeunt, sic circa meridianum cardinem, qui est propter inclinationem mundi subiectus terrae, sidera versabunda latentiaque non habent egressus orientis supra terram. itaque eorum figurationes propter obstantiam terrae non sunt notae. huius autem rei index est stella Canopi, quae his regionibus est ignota, renuntiant autem negotiatores, qui ad extremas Aegypti regiones proximasque ultimis finibus terrae terminationes fuerunt.

[¶13] 6.1. 1. I HAVE shown how the firmament, and the twelve signs with the constellations arranged to the north and south of them, fly round the earth, so that the matter may be clearly understood. For it is from this revolution of the firmament, from the course of the sun through the signs in the opposite direction, and from the shadows cast by equinoctial gnomons, that we find the figure of the analemma.

> Latin: 6.1. De mundi circa terram pervolitantia duodecimque signorum ex septentrionali meridianaque parte siderum dispositione, ut sit perspecta, docui. namque ex ea mundi versatione et contrario solis per signa cursu gnomonumque aequinoctialibus umbris analemmatorum inveniuntur descriptiones.

[¶14] 6.2. 2. As for the branch of astronomy which concerns the influences of the twelve signs, the five stars, the sun, and the moon upon human life, we must leave all this to the calculations of the Chaldeans, to whom belongs the art of casting nativities, which enables them to declare the past and the future by means of calculations based on the stars. These discoveries have been transmitted by the men of genius and great acuteness who sprang directly from the nation of the Chaldeans; first of all, by Berosus, who settled in the island state of Cos, and there opened a school. Afterwards Antipater pursued the subject; then there was Archinapolus, who also left rules for casting nativities, based not on the moment of birth but on that of conception.

> Latin: 6.2. Cetera ex astrologia, quos effectus habeant signa XII, stellae V, sol, luna ad humanae vitae rationem, Chaldaeorum ratiocinationibus est concedendum, quod propria est eorum genethlialogiae ratio, uti possint ante facta et futura ex ratiocinationibus astrorum explicare. eorum autem inventiones reliquerunt inque ⟨ea re⟩ sollertia acuminibusque fuerunt magnis, qui ab ipsa natione Chaldaeorum profluxerunt. primusque Berosus in insula et civitate Coo consedit ibique aperuit disciplinam, post ei studens Antipater iterumque Athenodorus, qui etiam non e nascentia sed ex conceptione genethlialogiae rationes explicatas reliquit.

[¶15] 6.3. 3. When we come to natural philosophy, however, Thales of Miletus, Anaxagoras of Clazomenae, Pythagoras of Samos, Xenophanes of Colophon, and Democritus of Abdera have in various ways investigated and left us the laws and the working of the laws by which nature governs it. In the track of their discoveries, Eudoxus, Euctemon, Callippus, Meto, Philippus, Hipparchus, Aratus, and others discovered the risings and settings of the constellations, as well as weather prognostications from astronomy through the study of the calendars, and this study they set forth and left to posterity. Their learning deserves the admiration of mankind; for they were so solicitous as even to be able to predict, long beforehand, with divining mind, the signs of the weather which was to follow in the future. On this subject, therefore, reference must be made to their labours and investigations.

> Latin: 6.3. De naturalibus autem rebus Thales Milesius, Anaxagoras Clazomenius, Pythagoras Samius, Xenophanes Colophonius, Democritus Abderites rationes, quibus e rebus natura rerum gubernaretur quemadmodum quaeque effectus habeat, excogitatas reliquerunt. quorum inventa secuti siderum ⟨ad ortus⟩ et occasus tempestatum significatus Eudoxus, Euctemon, Callippus, Meto, Philippus, Hipparchus, Aratus ceterique ex astrologia parapegmatorum disciplinis invenerunt et eas posteris explicatas reliquerunt. quorum scientiae sunt hominibus suspiciendae, quod tanta cura fuerunt, ut etiam videantur divina mente tempestatium significatus post futuros ante pronuntiare. quas ob res haec eorum curis studiisque sunt concedenda.

[¶16] 7.1. 1. IN distinction from the subjects first mentioned, we must ourselves explain the principles which govern the shortening and lengthening of the day. When the sun is at the equinoxes, that is, passing through Aries or Libra, he makes the gnomon cast a shadow equal to eight ninths of its own length, in the latitude of Rome. In Athens, the shadow is equal to three fourths of the length of the gnomon; at Rhodes to five sevenths; at Tarentum, to nine elevenths; at Alexandria, to three fifths; and so at other places it is found that the shadows of equinoctial gnomons are naturally different from one another.

> Latin: 7.1. Nobis autem ab his separandae sunt rationes et explicandae menstruae dierum brevitates itemque dilatationes. namque sol aequinoctiali tempore ariete libraque versando, quas e gnomone partes habet novem, eas umbrae facit VIII in declinatione caeli, quae est Romae. itemque Athenis quam magnae sunt gnomonis partes quattuor, umbrae sunt tres, ad VII Rhodo V, ad XI Tarenti IX, ad quinque ⟨Alexandriae⟩ tres, ceterisque omnibus locis aliae alio modo umbrae gnomonum aequinoctiales a natura rerum inveniuntur disparatae.

[¶17] 7.2. 2. Hence, wherever a sundial is to be constructed, we must take the equinoctial shadow of the place. If it is found to be, as in Rome, equal to eight ninths of the gnomon, let a line be drawn on a plane surface, and in the middle thereof erect a perpendicular, plumb to the line, which perpendicular is called the gnomon. Then, from the line in the plane, let the line of the gnomon be divided off by the compasses into nine parts, and take the point designating the ninth part as a centre, to be marked by the letter A. Then, opening the compasses from that centre to the line in the plane at the point B, describe a circle. This circle is called the meridian.

> Latin: 7.2. Itaque in quibuscumque locis horologia erunt describenda, eo loci sumenda est aequinoctialis umbra, et si erunt quemadmodum Romae gnomonis partes novem, umbrae octo, linea describatur in planitia et e media πρὸς ὀρθᾶς erigatur [ut sit ad normam] quae dicitur gnomon. et a linea, quae erit planities, in linea gnomonis circino novem spatia dimetiantur; et quo loco nonae partis signum fuerit, centrum constituatur, ubi erit littera A; et diducto circino ab eo centro ad lineam planitiae, ubi erit littera B, circinatio circuli describatur, quae dicitur meridiana.

[¶18] 7.3. 3. Then, of the nine parts between the plane and the centre on the gnomon, take eight, and mark them off on the line in the plane to the point C. This will be the equinoctial shadow of the gnomon. From that point, marked by C, let a line be drawn through the centre at the point A, and this will represent a ray of the sun at the equinox. Then, extending the compasses from the centre to the line in the plane, mark off the equidistant points E on the left and I on the right, on the two sides of the circumference, and let a line be drawn through the centre, dividing the circle into two equal semicircles. This line is called by mathematicians the horizon.

> Latin: 7.3. Deinde ex novem partibus, quae sunt a planitia ad gnomonis centrum,VIII sumantur et signentur in linea, quae est in planitia, ubi erit littera C. haec autem erit gnomonis aequinoctialis umbra. et ab eo signo et littera C per centrum, ubi est littera A, linea perducatur, ubi erit solis aequinoctialis radius. tunc a centro diducto circino ad lineam planitiae aequilatatio signetur, ubi erit littera E sinisteriore parte et D ulteriore in extremis lineae circinationis. et per centrum perducendum, ut aequa duo hemicyclia sint divisa. haec autem linea a mathematicis dicitur horizon.

[¶19] 7.4. 4. Then, take a fifteenth part of the entire circumference, and, placing the centre of the compasses on the circumference at the point where the equinoctial ray cuts it at the letter F, mark off the points G and H on the right and left. Then lines must be drawn from these (and the centre) to the line of the plane at the points T and R, and thus, one will represent the ray of the sun in winter, and the other the ray in summer. Opposite E will be the point I, where the line drawn through the centre at the point A cuts the circumference; opposite G and H will be the points L and K; and opposite C, F, and A will be the point N.

> Latin: 7.4. Deinde circinationis totius sumenda pars est XV; et circini centrum conlocandum in linea circinationis, quo loci secat eam lineam aequinoctialis radius, ubi erit littera F; et signandum dextra sinistra, ubi sunt litterae G H. deinde ab his ⟨et per centrum⟩ lineae usque ad lineam planitiae perducendae sunt, ubi erunt litterae I K. ita erit solis radius unus hibernus, alter aestivus. contra autem ⟨E⟩ littera D erit, qua secat circinationem linea, quae est traiecta per centrum, ubi ⟨est littera A; et contra G⟩ erunt litterae I et M; et contra H litterae erunt K et L; et contra C et F et A erit littera N.

[¶20] 7.5. 5. Then, diameters are to be drawn from G to L and from H to K. The upper will denote the summer and the lower the winter portion. These diameters are to be divided equally in the middle at the points M and 0, and those centres marked; then, through these marks and the centre A, draw a line extending to the two sides of the circumference at the points P and Q. This will be a line perpendicular to the equinoctial ray, and it is called in mathematical figures the axis. From these same centres open the compasses to the ends of the diameters, and describe semicircles, one of which will be for summer and the other for winter.

> Latin: 7.5. Tunc perducendae sunt διαμέτρω ab G ad L et ab H ⟨ad M⟩. quae erit superior, partis erit aestivae, inferior hibernae. eaeque διαμέτρω sunt aeque mediae dividendae, ubi erunt litterae O et P, ibique centra signanda. et per ea signa et centrum A lineae ad extrema lineae circinationis sunt perducendae, ubi erunt litterae Q et R. haec erit linea πρὸς ὀρθᾶς radio aequinoctiali. vocabitur autem haec linea mathematicis rationibus axon. et ab eisdem centris diducto circino ad extremas diametros describantur hemicyclia, quorum unum erit aestivum, alterum hibernum.

[¶21] 7.6. 6. Then, at the points at which the parallel lines cut the line called the horizon, the letter S is to be on the right and the letter V on the left, and from the extremity of the semicircle, at the point G, draw a line parallel to the axis, extending to the left-hand semicircle at the point H. This parallel line is called the Logotomus. Then, centre the compasses at the point where the equinoctial ray cuts that line, at the letter D, and open them to the point where the summer ray cuts the circumference at the letter H. From the equinoctial centre, with a radius extending to the summer ray, describe the circumference of the circle of the months, which is called Menaeus. Thus we shall have the figure of the analemma.

> Latin: 7.6. Deinde in quibus locis secant lineae paralleloe lineam eam quae dicitur horizon, in dexteriore parte erit littera S, in sinisteriore T. et ab littera S ducatur linea parallelos axoni ad extremum ⟨dextrum⟩ hemicyclium, ubi erit littera V; et ab T ad sinistrum hemicyclium item parallelos linea ducatur ad litteram X. haec autem paralleloe lineae vocitantur †locothomus. et tum circini centrum conlocandum est eo loci, quo secat circinationem aequinoctialis radius, ubi erit littera F; et diducendum ad eum locum, quo secat circinationem aestivus radius, ubi est littera H. e centro aequinoctiali intervallo aestivo circinatio circuli menstrui agatur, qui menaeus dicitur. ita habebitur analemmatos deformatio.

[¶22] 7.7. 7. This having been drawn and completed, the scheme of hours is next to be drawn on the baseplates from the analemma, according to the winter lines, or those of summer, or the equinoxes, or the months, and thus many different kinds of dials may be laid down and drawn by this ingenious method. But the result of all these shapes and designs is in one respect the same: namely, the days of the equinoxes and of the winter and summer solstices are always divided into twelve equal parts. Omitting details, therefore,—not for fear of the trouble, but lest I should prove tiresome by writing too much,—I will state by whom the different classes and designs of dials have been invented. For I cannot invent new kinds myself at this late day, nor do I think that I ought to display the inventions of others as my own. Hence, I will mention those that have come down to us, and by whom they were invented.

> Latin: 7.7. Cum hoc ita sit descriptum et explicatum, sive per hibernas lineas sive per aestivas sive per aequinoctiales aut etiam per menstruas in subiectionibus rationes horarum erunt ex analemmatos describendae, subiciunturque in eo multae varietates et genera horologiorum et describuntur rationibus his artificiosis. omnium autem figurarum descriptionumque earum effectus unus, uti dies aequinoctialis brumalisque itemque solstitialis in duodecim partes aequaliter sit divisus. quas ob res non pigritia deterritus praetermisi, sed ne multa scribendo offendam, a quibusque inventa sunt genera descriptionesque horologiorum, exponam. neque enim nunc nova genera invenire possum nec aliena pro meis praedicanda videntur. itaque quae nobis tradita sunt et a quibus sint inventa, dicam.

[¶23] 8.1. 1. THE semicircular form, hollowed out of a square block, and cut under to correspond to the polar altitude, is said to have been invented by Berosus the Chaldean; the Scaphe or Hemisphere, by Aristarchus of Samos, as well as the disc on a plane surface; the Arachne, by the astronomer Eudoxus or, as some say, by Apollonius; the Plinthium or Lacunar, like the one placed in the Circus Flaminius, by Scopinas of Syracuse; the πρὸς τὰ ἱστοπούμενα Parmenio; the πρὸς πᾶν κλῖμα, by Theodosius and Andreas; the Pelecinum, by Patrocles; the Cone, by Dionysodorus; the Quiver, by Apollonius. The men whose names are written above, as well as many others, have invented and left us other kinds: as, for instance, the Conarachne, the Conical Plinthium, and the Antiborean. Many have also left us written directions for making dials of these kinds for travellers, which can be hung up. Whoever wishes to find their baseplates, can easily do so from the books of these writers, provided only he understands the figure of the analemma.

> Latin: 8.1. Hemicyclium excavatum ex quadrato ad enclimaque succisum Berosus Chaldaeus dicitur invenisse; scaphen sive hemisphaerium Aristarchus Samius, idem etiam discum in planitia; arachnen Eudoxus astrologus, nonnulli dicunt Apollonium; plinthium sive lacunar, quod etiam in circo Flaminio est positum, Scopinas Syracusius; πρὸς τὰ ἱστορούμενα Parmenion, πρὸς πᾶν κλῖμα Theodosius et Andrias, Patrocles pelecinum, Dionysodorus conum, Apollonius pharetram, aliaque genera et qui supra scripti sunt et alii plures inventa reliquerunt, uti conarachnen, conicum plinthium, antiboreum. item ex his generibus viatoria pensilia uti fierent, plures scripta reliquerunt. ex quorum libris, si qui velit, subiectiones invenire poterit, dummodo sciat analemmatos descriptiones.

[¶24] 8.2. 2. Methods of making water clocks have been investigated by the same writers, and first of all by Ctesibius the Alexandrian, who also discovered the natural pressure of the air and pneumatic principles. It is worth while for students to know how these discoveries came about. Ctesibius, born at Alexandria, was the son of a barber. Preeminent for natural ability and great industry, he is said to have amused himself with ingenious devices. For example, wishing to hang a mirror in his father's shop in such a way that, on being lowered and raised again, its weight should be raised by means of a concealed cord, he employed the following mechanical contrivance.

> Latin: 8.2. Item sunt ex aqua conquisitae ab eisdem scriptoribus horologiorum rationes, primumque a Ctesibio Alexandrino, qui et vim spiritus naturalis pneumaticasque res invenit. sed uti fuerint ea exquisita, dignum studiosis agnoscere. Ctesibius enim fuerat Alexandriae natus patre tonsore. is ingenio et industria magna praeter reliquos excellens dictus est artificiosis rebus se delectare. namque cum voluisset in taberna sui patris speculum ita pendere, ut, cum duceretur susumque reduceretur, linea latens pondus deduceret, ita conlocavit machinationem.

[¶25] 8.3. 3. Under the roof-beam he fixed a wooden channel in which he arranged a block of pulleys. He carried the cord along the channel to the corner, where he set up some small piping. Into this a leaden ball, attached to the cord, was made to descend. As the weight fell into the narrow limits of the pipe, it naturally compressed the enclosed air, and, as its fall was rapid, it forced the mass of compressed air through the outlet into the open air, thus producing a distinct sound by the concussion.

> Latin: 8.3. Canalem ligneum sub tigno fixit ibique trocleas conlocavit; per canalem lineam in angulum deduxit ibique tubulos struxit; in eos pilam plumbeam per lineam demittendam curavit. ita pondus cum decurrendo in angustias tubulorum premeret caeli crebritatem, vehementi decursu per fauces frequentiam caeli compressione solidatam extrudens in aerem patentem effusione acuti sonitus expresserat claritatem.

[¶26] 8.4. 4. Hence, Ctesibius, observing that sounds and tones were produced by the contact between the free air and that which was forced from the pipe, made use of this principle in the construction of the first water organs. He also devised methods of raising water, automatic contrivances, and amusing things of many kinds, including among them the construction of water clocks. He began by making an orifice in a piece of gold, or by perforating a gem, because these substances are not worn by the action of water, and do not collect dirt so as to get stopped up.

> Latin: 8.4. Ergo Ctesibius cum animadvertisset ex tractu caeli et expressionibus spiritus ⟨sonitus⟩ vocesque nasci, his principiis usus hydraulicas machinas primus instituit. item aquarum expressiones automatopoetasque machinas multaque deliciarum genera, in his etiam horologiorum ex aqua comparationes explicuit. primumque constituit cavum ex auro perfectum aut ex gemma terebrata; ea enim nec teruntur percussu aquae nec sordes recipiunt, ut obturentur.

[¶27] 8.5. 5. A regular flow of water through the orifice raises an inverted bowl, called by mechanicians the “cork” or “drum.” To this are attached a rack and a revolving drum, both fitted with teeth at regular intervals. These teeth, acting upon one another, induce a measured revolution and movement. Other racks and other drums, similarly toothed and subject to the same motion, give rise by their revolution to various kinds of motions, by which figures are moved, cones revolve, pebbles or eggs fall, trumpets sound, and other incidental effects take place.

> Latin: 8.5. Namque aequaliter per id cavum influens aqua sublevat scaphium inversum, quod ab artificibus phellos sive tympanum dicitur. in quo conlocata est regula ⟨iuxta⟩ versatile tympanum. denticulis aequalibus sunt perfecta, qui denticuli alius alium inpellentes versationes modicas faciunt et motiones. item aliae regulae aliaque tympana ad eundem modum dentata una motione coacta versando faciunt effectus varietatesque motionum, quibus moventur sigilla, vertuntur metae, calculi aut ova proiciuntur, bucinae canunt, reliquaque parerga.

[¶28] 8.6. 6. The hours are marked in these clocks on a column or a pilaster, and a figure emerging from the bottom points to them with a rod throughout the whole day. Their decrease or increase in length with the different days and months, must be adjusted by inserting or withdrawing wedges. The shutoffs for regulating the water are constructed as follows. Two cones are made, one solid and the other hollow, turned on a lathe so that one will go into the other and fit it perfectly. A rod is used to loosen or to bring them together, thus causing the water to flow rapidly or slowly into the vessels. According to these rules, and by this mechanism, water clocks may be constructed for use in winter.

> Latin: 8.6. In his etiam aut in columna aut parastatica horae describuntur, quas sigillum egrediens ab imo virgula significat in diem totum. quarum brevitates aut crescentias cuneorum adiectus aut exemptus in singulis diebus et mensibus perficere cogit. praeclusiones aquarum ad temperandum ita sunt constitutae. metae fiunt duae, una solida, una cava, ex torno ita perfectae, ut alia in aliam inire convenireque possit et eadem regula laxatio earum aut coartatio efficiat aut vehementem aut lenem in ea vasa aquae influentem cursum. ita his rationibus et machinatione ex aqua componuntur horologiorum ad hibernum usum conlocationes.

[¶29] 8.7. 7. But if it proves that the shortening or lengthening of the day is not in agreement with the insertion and removal of the wedges, because the wedges may very often cause errors, the following arrangement will have to be made. Let the hours be marked off transversely on the column from the analemma, and let the lines of the months also be marked upon the column. Then let the column be made to revolve, in such a way that, as it turns continuously towards the figure and the rod with which the emerging figure points to the hours, it may make the hours short or long according to the respective months.

> Latin: 8.7. Sin autem cuneorum adiectionibus et detractionibus correptiones dierum aut crescentiae †ex cuneis non probabuntur fieri, quod cunei saepissime vitia faciunt, sic erit explicandum. in columella horae ex analemmatos transverse describantur, menstruaeque lineae columella signentur. eaque columna versatilis perficiatur, uti ad sigillum virgulamque, qua virgula egrediens sigillum ostendit horas, columna versando continenter suis cuiusque mensibus brevitates et crescentias faciat horarum.

[¶30] 8.8. 8. There is also another kind of winter dial, called the Anaphoric and constructed in the following way. The hours, indicated by bronze rods in accordance with the figure of the analemma, radiate from a centre on the face. Circles are described upon it, marking the limits of the months. Behind these rods there is a drum, on which is drawn and painted the firmament with the circle of the signs. In drawing the figures of the twelve celestial signs, one is represented larger and the next smaller, proceeding from the centre. Into the back of the drum, in the middle, a revolving axis is inserted, and round that axis is wound a flexible bronze chain, at one end of which hangs the “cork” which is raised by the water, and at the other a counterpoise of sand, equal in weight to the “cork.”

> Latin: 8.8. Fiunt etiam alio genere horologia hiberna, quae anaphorica dicuntur perficiunturque rationibus his. horae disponuntur ex virgulis aeneis ex analemmatos descriptione ab centro dispositae in fronte; in ea circuli sunt circumdati menstrua spatia finientes. post has virgulas tympanum, in quo descriptus et depictus est mundus signiferque circulus [descriptioque ex XII caelestium signorum fit figurata], cuius ex centro deformatio … unum maius, alterum minus. posteriori autem parte tympano medio axis versatilis est inclusus inque eo axi aenea mollis catena est involuta, ex qua pendet ex una parte phellos (sive tympanum), qui ab aqua sublevatur, altera aequo pondere phelli sacoma saburrale.

[¶31] 8.9. 9. Hence, the sand sinks as the “cork” is raised by the water, and in sinking turns the axis, and the axis the drum. The revolution of this drum causes sometimes a larger and sometimes a smaller portion of the circle of the signs to indicate, during the revolutions, the proper length of the hours corresponding to their seasons. For in every one of the signs there are as many holes as the corresponding month has days, and a boss, which seems to be holding the representation of the sun on a dial, designates the spaces for the hours. This, as it is carried from hole to hole, completes the circuit of a full month.

> Latin: 8.9. Ita quantum ab aqua phellos sublevatur, tantum saburrae pondus infra deducens versat axem, axis autem tympanum. cuius tympani versatio alias efficit, uti maior pars circuli signiferi, alias minor in versationibus suis temporibus designet horarum proprietates. namque in singulis signis sui cuiusque mensis dierum numeri cava sunt perfecta, cuius bulla, quae solis imaginem horologiis tenere videtur, significat horarum spatia. ea translata ex terebratione in terebrationem mensis vertentis perficit cursum suum.

[¶32] 8.10. 10. Hence, just as the sun during his passage through the constellations makes the days and hours longer or shorter, so the boss on a dial, moving from point to point in a direction contrary to that of the revolution of the drum in the middle, is carried day by day sometimes over wider and sometimes over narrower spaces, giving a representation of the hours and days within the limits of each month. To manage the water so that it may flow regularly, we must proceed as follows.

> Latin: 8.10. Itaque quemadmodum sol per siderum spatia vadens dilatat contrahitque dies et horas, sic bulla in horologiis ingrediens per puncta contra centri tympani versationem, cotidie cum transfertur aliis temporibus per latiora, aliis per angustiora spatia, menstruis finitionibus imagines efficit horarum et dierum. De administratione autem aquae, quemadmodum se temperet ad rationem, sic erit faciendum.

[¶33] 8.11. 11. Inside, behind the face of the dial, place a reservoir, and let the water run down into it through a pipe, and let it have a hole at the bottom. Fastened to it is a bronze drum with an opening through which the water flows into it from the reservoir. Enclosed in this drum there is a smaller one, the two being perfectly jointed together by tenon and socket, in such a way that the smaller drum revolves closely but easily in the larger, like a stopcock.

> Latin: 8.11. Post frontem horologii intra conlocetur castellum in idque per fistulam saliat aqua et in imo habeat cavum. ad id autem adfixum sit ex aere tympanum habens foramen, per quod ex castello in id aqua influat. in eo autem minus tympanum includatur cardinibus ex torno masculo et femina inter se coartatis, ita uti minus tympanum quemadmodum epitonium in maiore circumagendo arte leniterque versetur.

[¶34] 8.12. 12. On the lip of the larger drum there are three hundred and sixty-five points, marked off at equal intervals. The rim of the smaller one has a tongue fixed on its circumference, with the tip directed towards those points; and also in this rim is a small opening, through which water runs into the drum and keeps the works going. The figures of the celestial signs being on the lip of the larger drum, and this drum being motionless, let the sign Cancer be drawn at the top, with Capricornus perpendicular to it at the bottom, Libra at the spectator's right, Aries at his left, and let the other signs be given places between them as they are seen in the heavens.

> Latin: 8.12. Maioris autem tympani labrum aequis intervallis CCCLXV puncta habeat signata, minor vero orbiculus in extrema circinatione fixam habeat lingulam, cuius cacumen dirigat ad punctorum regiones, inque eo orbiculo temperatum sit foramen, quia in tympanum aqua influit per id et servat administrationem. cum autem in maioris tympani labro fuerint signorum caelestium deformationes, id autem sit inmotum et in summo habeat deformatum cancri signum, ad perpendiculum eius in imo capricorni, ad dextram spectantis librae, ad sinistram arietis signum, ceteraque inter eorum spatia designata sint, uti in caelo videntur:

[¶35] 8.13. 13. Hence, when the sun is in Capricornus, the tongue on the rim touches every day one of the points in Capricornus on the lip of the larger drum, and is perpendicular to the strong pressure of the running water. So the water is quickly driven through the opening in the rim to the inside of the vessel, which, receiving it and soon becoming full, shortens and diminishes the length of the days and hours. But when, owing to the daily revolution of the smaller drum, its tongue reaches the points in Aquarius, the opening will no longer be perpendicular, and the water must give up its vigorous flow and run in a slower stream. Thus, the less the velocity with which the vessel receives the water, the more the length of the days is increased.

> Latin: 8.13. Igitur cum sol fuerit in capricorni, orbiculi lingula in maioris tympani parte ex capricorni cotidie singula puncta tangens, ad perpendiculum habens aquae currentis vehemens pondus, celeriter per orbiculi foramen id extrudit ad vasum excipiens eam. cum brevi spatio impletur, corripit et contrahit dierum spatia et horarum. cum autem cotidiana versatione minoris tympani lingula ingrediatur in aquarii puncta, discedens foramen a perpendiculo et aquae vehementi cursu cogitur tardius emittere salientem. ita quo minus celeri cursu vas excipit aquam, dilatat horarum spatia.

[¶36] 8.14. 14. Then the opening in the rim passes from point to point in Aquarius and Pisces, as though going upstairs, and when it reaches the end of the first eighth of Aries, the fall of the water is of medium strength, indicating the equinoctial hours. From Aries the opening passes, with the revolution of the drum, through Taurus and Gemini to the highest point at the end of the first eighth of Cancer, and when it reaches that point, the power diminishes, and hence, with the slower flow, its delay lengthens the days in the sign Cancer, producing the hours of the summer solstice. From Cancer it begins to decline, and during its return it passes through Leo and Virgo to the points at the end of the first eighth of Libra, gradually shortening and diminishing the length of the hours, until it comes to the points in Libra, where it makes the hours equinoctial once more.

> Latin: 8.14. Aquarii vero pisciumque punctis uti gradibus scandens orbiculi foramen in ariete tangendo octavam partem aqua temperate salienti praestat aequinoctiales horas. ab ariete per tauri et geminorum spatia ad summa cancri puncta partis octavae foramen se tympani versationibus peragens et in altitudinem eo rediens viribus extenuatur, et ita tardius fluendo dilatat morando spatia et efficit horas in cancri signo solstitiales. a cancro cum proclinat et peragit per leonem et virginem ad librae partis octavae puncta revertendo et gradatim corripiendo spatia contrahit horas, et ita perveniens ad puncta librae aequinoctiales rursus reddit horas.

[¶37] 8.15. 15. Finally, the opening comes down more rapidly through Scorpio and Sagittarius, and on its return from its revolution to the end of the first eighth of Capricornus, the velocity of the stream renews once more the short hours of the winter solstice. The rules and forms of construction employed in designing dials have now been described as well as I could. It remains to give an account of machines and their principles. In order to make my treatise on architecture complete, I will begin to write on this subject in the following book.

> Latin: 8.15. Per scorpionis vero spatia et sagittarii proclivius deprimens se foramen rediensque circumactione ad capricorni partem VII, restituit celeritate salientis brumales horarum brevitates. Quae sunt in horologiorum descriptionibus rationes et apparatus, ut sint ad usum expeditiores, quam apertissime potui, perscripsi. restat nunc de machinationibus et de earum principiis ratiocinari. itaque de his, ut corpus emendatum architecturae perficiatur, insequenti volumine incipiam scribere.