Vitruvius Pollio (? 50 -26 B.C.) is the author of a remarkable book on the art of Architecture, which was published probably in 28 B.C., and was for the Romans and much later for the world of the classical Renaissance, the master treatise on the art of building. But it was far more than that, it ranges in its ten books over everything of interest and importance to the building trades, from the mixing of mortar from proper materials, to the acoustics in a stone threaten, and even to the art work which as fresco style was used to decorate gentlefolks' villas. There is little that Vitruvius did not touch on, one way or another.

His books had a huge influence on the West since l500, and only well into the 20th century did its influence start to break down with the new ideas from the BauHaus and modernism, along with the use of steel as the primary building material for large edifices. If you see Post Offices everywhere with Roman imitation columns in front, that is a sign that Vitruvius has been there.

Classicists tend to be literary snobs, and always remark that his writing "has no literary merit...". But his style is one of the few remaining examples of how Romans actually wrote down their information, how they documented their extensive knowledge in a dozen areas from construction of building, to medicine, to law. So I have made a selection of a few pages of Vitruvius as an example of that rare phenomenon ---- "ordinary Latin writing". Caesar's commentaries are stylistically extraordinary, not at all what they seem to the student puzzling over the ablative absolutes and indirect discourse. Plautus has passages which even in verse are ordinary, but all is cast in a Grecizing play format, so you Ave to extract the ordinary wording from what is after all a comic play.

Vitruvius is excellent reading for two reasons. First he is easy to read, no complex sentences, no arty separation of noun from adjective, and this is first rate practice reading for someone developing a reading knowledge. Second, he has content, something often lacking in the later writers like Statius and the imperial poets. What he writes can be seen in the remains of Roman a]buildings like the Pantheon, in the wall frescos, in the aqueducts. Moreover there is something respectable in the writing of a man who was a contractor, who knew how mortar and bricks go together, in short a man who knew what he was talking about. Cato, Varro, Columella, Celsus and "Gaius" the lawyer were near the center of the Roman experience, and some respect is due to their homely and plain language, which was the cement and brickwork of the Roman world.

De Architectura

Architecti est scientia pluribus disciplinis et variis eruditionibus ornata, quae ab ceteris artibus perficiuntur. Opera ea nascitur et fabrica et ratiocinatione. Fabrica est continuata ac trita usus meditatio, quae manibus perficitur e materia cuiuscumque generis opus est ad propositum deformationis. Ratiocinatio autem est. quae res fabricatas sollertiae ac rationis proportione demonstrare atque explicare potest.

Here at last appears a word which you will seldom see in Latin writings, Fabrica which is generally parallel to the Greek techne, but with an essential difference. In the works of Plato you find the handicrafts and skills deprecated, and the Greeks went to great efforts to hide the fact that hand based skills were responsibly for much of their economy and civilization. Aristotle did recognize the "hand" as the organon organwn (gen. pl.), the tool which makes tools, and modern thought often refers to the hand as "the cutting edge of the mind". If fabrica is the manual side of a craft, ratio and ratiocinatio are the abstract or planning side of technology, although we seem to have merged the two notions in recent years.

Itaque architecti, qui sine litteris contenderant, ut manibus essent exercitati, non potuerunt efficere, ut haberent pro laboribus auctoritatem. Qui autem ratiocinationibus et litteris solis confisi fuerunt, umbram non rem persecuti videntur. At qui utrumque perdidicerunt, uti omnibus armis ornati citius cum auctoritate, quod fuit propositum, sunt adsecuti. /p>

Litterae here means "education", not the literary side of an education, a common misapprehension. He puts this in perfect perspective, since without a wide educated base, the craftsman is a mere technician, whereas the abstract theoretician (as an architect who does elegant drawings but has no experience with construction) is working with something like "shadows", abstract statements with no finite reality.

Cum in omnibus enim rebus, tum maxime etiam in architectura haec duo insunt, quod significatur et quod significant. Significatur proposita res, de qua dicitur. Hanc autem significat demonstratio rationibus doctrinarum explicata. Quare videtur utraque parte exercitatus esse debere, qui se architectum profiteatur. Itaque eum etiam ingeniosum oportet esse et ad disciplinam, docilem. Neque enim ingenium sine disciplina aut disciplina sine ingenio perfectum artificem potest efficere. Et ut litteratus sit, peritus graphidos, eruditus geometria, historias complures noverit, philosophos diligenter audierit, musicam scierit, medicinae non sit ignarus responsa iurisconsultorum noverit, astrologiam caelique rationes cognitas habeat.

Remember that the Latin language makes much more of this split between factual and irrealis than we do in English, and this sentence was probably clearer to Romans than to us.

Ingeniosus is not like the English cognate, it means "having a natural talent", but must be teachable or "docilis" (again not the English docile). What follows is much like the Liberal Arts prerequisite before you apply for Architecture Grad School, perhaps more cogent here than in electrical engineering or even medicine.<

Historias autem plures novisse oportet, quod multa ornamenta saepe in operibus architecti designant, de quibus argumentis rationem, cur fecerint, quaerentibus reddere debent. Quemadmodum si quis statuas marmoreas muliebres stolatas, quae cariatides dicuntur, pro columnis in opere statuerit et insuper mutulos et coronas conlocaverit, percontantibus ita reddet rationem Caria, civitas Peloponnensis, cum Persis hostibus contra Graeciam consensit. Postea Graeci per victoriam gloriose bello liberati communi consilio Cariatibus bellum indixerunt. ltaque oppido capto, viris interfectis, civitate declarata matronas eorum in servitutem abduxerunt, nec sunt passi stolas neque ornatus matronales deponere, uti non una triumpho ducerentur, sed aeterno, servitutis exemplo gravi contumelia pressae poenas pendere viderentur pro civitate. Ideo qui tunc architecti fuerunt aedificiis publicis designaverunt earum imagines oneri ferundo conlocatas, ut etiam posteris nota poena peccati Cariatium memoriae traderetur.

Clearly within the range of "Education" is the field of History, and Vitruvius has an idea which has been important in modern times in every country, that the decoration of a building should have some historical or social significance. Worker sculpture and friezes on architectural work ranges from the early USSR to the US in the Works Projects of the l930's, and Vitruvius has a try at an explanation of the Caryatids on his own. Scholars have always seen them as a ritual processional, but here they are portrayed as a political warning to those who might revolt, as in the Carian situation. This is clever, something like a retro-etymology, and surely incorrect. But it does try to make a reason for an improbable situation, marble architraves on girls' head!.

Item theatris vasa area, quae in cellis sub gradibus mathematica ratione conlocantur quae Gracei echeia appellant. Sonit×m et discrimina ad symphonias musicas sive concentus componuntur divisa in circinatione diatesseron et diapente et disdiapason, uti vox scaenici sonitus conveniens in dispositionibus tactu cum offenderit, aucta cum incremento clarior et suavior ad spectatorum perveniat aures.

I include this description of the theater for a specific reasons, since this is the explanation of the "sounding brass" of St Paul's Corinthians I 13, which nobody understands. In the niches around the theater were placed bronze (in Italy earthenware) Helmholtz resonators, aperture-tuned to series of regular intervals, to serve as passive amplifiers to the speech or music going on at the center of the stage. We see niches in all ancient theaters, but the bronze vases are long sine gone into counterfeit coinage. This is what Paul mean by saying "You are as sounding brass (jars), noise without meaning". The case if further describe in detail in Book V on Acoustics.

Disciplinam vero medicinae novisse oportet propter inclinationem caeli, quae Graeci climata dicunt, et aeris et locorum, qui sunt salubres aut pestilentes, aquarumque usus. Sine his enim rationibus nulla salubris habitatio fieri potest. Iura quoque nota habeat oportet, ea quae necessaria sunt aedificiis communibus parietum ad ambitum stillicidiorum et cloacarum, luminum. Item, aquarum ductiones et cetera quae eiusmod sunt, nota oportet sint architectis, uti ante caveant quam instituant aedificia, ne controversiae factis operibus patribus familiarum relinquantur, et ut legibus scribendis prudentia cavere possit et locatori et conductori. Namque si lex perite fuerit scripta. Erit ut sine captione uterque ab utroque liberetur. Ex astrologia autem cognoscitur oriens, occidens, meridies, septentrio, etiam caeli ratio, aequinoctium, solstitium, astrorum cursus. Quorum notitiam si quis non habuerit, horologiorum rationem omnino scire non poterit.

Here is a whole range of assorted concerns for the architect, from his reading of Hippocrates De Aere Aquis Locis, to easements in deeds, blocking of neighbors' light (Gaius II 14, and these were commonly understood items to be watched with care, as Cicero notes De Oratore I, l73 as "iura parietum, luminum, stillicidiorum". Leges are specifically written Contracts, the regular terms for land related dealings.
Under Astrology he clearly means astronomy, although in this time our "Astrology" was current for ancient times. But he is a practical man and sees this for telling time exactly, the days of contractual arrangements, dates for constructions, and even clocks which he go into in Book 9. <

Ac fortasse mirum videbitur inperitis hominibus posse naturam tantum numerum doctrinarum perdiscere et memoria continere. Cum autem animadverterint omnes disciplinas inter se coniunctionem rerum et communicationem habere, fieri posse faciliter credent. Encyclios enim disciplina uti corpus unum ex his membris est composita. Itaque qui a teneris aetatibus eruditionibus variis instruuntur, omnibus litteris agnoscunt easdem notas communicationemque omnium disciplinarum, et ea re facilius omnia cognoscunt. Ideoque de veteribus architectis Pythius, qui Prieni aedem Minervae nobiliter est architectatus, ait in suis commentariis architectum omnibus artibus et doctrinis plus oportere posse facere, quam qui singulas res suis industriis et exercitationibus ad summam claritatem perduxerunt. Id autem re non expeditur

Again he stresses wide knowledge, a far reaching education, with reasonable understanding of the great Hellenic tradition, as befitted a man living in the high educated world of Virgil and Horace. But at heart there is something of the working man in Vitruvius, even when he quotes from his book-knowledge what architect Pythius said about his field being the highest. Cicero would have known from Aristotle that arete was the most architectonic, a point probably wasted on our good writer. BUT, he had at the end that he is not sure about all this stuff. (The last sentence is critical, from the wording surely not a late gloss.)

Cum ergo talia ingenia ab naturali sollertia non passim cunctis gentibus sed paucis viris habere concedatur, officium vero architecti omnibus eruditionibus debeat esse exercitatum, et ratio propter amplitudinem rei permittat non iuxta necessitatem summas sed etiam mediocris scientias habere disciplinarum, peto, Caesar, et a te et ab is, qui ea volumina sunt lecturi, ut, si quid parum ad regulam artis grammaticae fuerit explicatum, ignoscatur. Namque non uti summus philisophus nec rhetor disertus nec grammaticus summis rationibus artis exercitatus, sed ut architectus his litteris inbutus haec nisus sum scribere. De artis vero potestate quaeque insunt in ea ratiocinationes polliceor uti spero, his voluminibus non modo aedificantibus sed etiam omnibus sapientibus cum maxima auctoritate me sine dubio praestaturum.

Now Vitruvius catches himself as perhaps having spoken too boldly, a practical engineering man without the full scope of "education" as suiting the August Personage to whom he was dedicating this work, and incidentally getting his living as top architect for the empire. No literary man am I, but a man of talent and craft, and so we proceed to the following treatises on Architectura.
The Romans early discovered how much could be done with mortar blinding stones (opus incertum) and then bricks into walls, which could later as August bragged, could under his administration be covered with thin marble facing. "I found Rome brick, left it marble". But it was with pour concrete that Rome made its mark, not only in harbor works, foundations and military barricading, but in major architectural construction. Vitruvius' book was published after 27 B.C. since he addresses Octavian as Caesar. Agrippa's magnificent cast concrete Pantheon dates from 28 B.C., and our author is thought to have died in 26 B.C. So he was in the high early development of concrete work as technology and as imaginative architecture, without doubt he witnessed the casting of the Pantheon.
Therefore citing his materials on Sand and Cement Lime seems unusually pertinent at this point. These two longer passage are not easy to read, but they are of great importance historically and technically, so I have cited them in full. If you are interested, push on, but I advise trying to get through the details with a clear eye on what he is saying. Reading something that is hard to understand is the best way to improve reading skills, and I suspect that if you can get through these passages intact, you will have come ahead.


In caementiciis autem structuris primum est de harena quaerendum, ut ea sit idonea ad materiem miscendam neque habeat terram commixtam. Genera autem harenae fossiciae sunt haec: nigra, cana, rubra, carbunculum. Ex his, quae in manu confricata, vel icta fecerit stridorem, erit optima. Quae autem terrosa fuerit, non habebit asperitatem. Item si in vestimentum candidum ea contecta fuerit, postea excussa aut icta id non inquinarit neque ibi terra subsiderit, erit idonea.

The carbunculum will have coal like deposits. THe cloth test is not to sieve it but to test if there is finely divided particulate matters, which will impede concrete setting.

Sin autem non erunt harenaria, unde fodiatur, tum de fluminibus aut e glarea erit excernenda, non minus etiam de litore marino. Sed ea in structuris haec habebat vitia: difficulter siccescit, neque onerari se continenter recipit. Paries patitur, nisi intermissionibus requiescat, neque concamerationes recipit. Marina autem hoc amplius, quod etiam parietes, cum in is tectoria facta fuerint, remittentes salsuginem eorum dissolvuntur.

Note that "siccescit" refers not to sand but the concrete made up with this kind of sand. The concamerationes are cast concerete vaulting, as used extensively in the new Pantheon.

Fossiciae vero celeriter in structuris siccescunt, et tectoria permanent, et concamerationes patiuntur, sed hae, quae sunt de harenariis recentes. Si enim exemptae diutius iacent, ab sole et luna et pruina concoctae resolvuntur et fiunt terrosae.

The word sed means "but only those", i.e. fresh from the sandpit. Of course it is the air deposits, not the sun moon and frost/dew which make them dirty.

Ita cum in structuram coiciuntur, non possunt continere caementa, sed ea ruunt et labuntur oneraque paritetes non possunt sustinere. Recentes autem fossiciae cum in structuris tantas habeant virtutes, eae in tectoriis ideo non sunt utiles, quod pinguitudini eius calx palea commixta, propter vehementiam non potest sine rimis inarescere. Fluviatica vero propter macritatem uti signinum liaculorum subactionibus in tectorio recipit soliditatem.

If river sand being finer is best for roofing mortar with tiles, then the bank sand must be too rich (pinguis) when mixed with straw as in bricks. Modern texts on concrete still use the word "fat" for lime in its pure unsanded state. And then vehementia is its strength or stiffness which does not allow movement, hence cracking. In other words rough sand makes a mini-concrete, not good for a mortar because of its rigidity.<


De harenae copiis cum habeatur explicatum, tum etiam de calce diligentia est adhibenda, uti de albo saxo aut silice coquatur. Et quae erit ex spisso et duriore, erit utilis in structura, quae autem ex fistuloso, in tectoriis. Cum ea erit extincta, tunc materia ita misceatur, ut, si erit fossicia, tres harenae et una calcis infundatur. This calx is lime, to be ground from stone or lava quarried silex. After bring burned to drive off the carbonic acid, it reacts violently with water to become "slaked" lime, which when mixed with a sandy material as aggregate, it dries purely by evaporation of the water, with no chemical action involved. This becomes Mortar for tile or brickwork. Superficial hardening takes place by absorption of carbonic acid from the air by the lime. This is still not the Concrete of which more below...

Si autem fluviatica aut marina, duo harenae una calcis coiciatur. Ita enim erit iusta ratio mixtionis temperaturae. Etiam in fluviatica aut marina si qui testam tunsam et succretam ex tertia parte adiecerit, efficiet materiae temperaturam ad usum meliorem. Three shovels of sand to one of cement, still the working rule of men on the job today, and a proportion used in bagged sand mixes.

Quare autem cum recipit aquam et harenam calx, tunc confirmat structuram, haec esse causa videtur, quod e principiis uti cetera corpora, ita et saxa sunt temperata. Et quae plus habent aeris, sunt tenera; quae aquae, lenta sunt ab umore; quae terrae, dura; quae ignis, fragiliora. Itaque ex his saxa si, antequam coquantur, contusa minute mixta harenae in instructuram coinciatur, non solidescunt nec eam poterunt continere. Cum vero coniecta in fornacem ignis vehementi fervore correpta amiserint pristinae soliditatis virtutem, tunc exustis atque exhaustis eorum viribus relinquuntur patientibus foraminibus et inanibus.

Not having a knowledge of the chemistry of the situation, Vitruvius posits "openings" and vacuities which enable the constituents to sieze up. But the reference to heating in the kiln point to an intuitive grasp of something being burned out, which is the water in combination.

Ergo liquor, qui est in eius lapidis corpore, et aer cum exustus et ereptus fuerit, habueritque in se residuum valorem latentem, intinctus in aqua, prius quam ex igni vim recepit umore penetrante in foraminum raritates, confervescit et ita refrigeratus reicit ex calcis corpore fervorem.

(Ideo autem, quo pondere saxa coiciuntur in fornacem, cum eximuntur, non possunt ad id respondere, sed cum expenduntur, permanente ea magnitudine excocto liquore circiter tertia parte ponderis inminuta esse inveniuntur.)

He knows of weight testing to determine the amount of water driven out of comination by the burning of the material. This had antecedents in Greek experimentation with frozen and melted water (Hippocrates) and gold tested for purity by weight by Archimedes. Most of Vitruvius' sources were Greek, as he states elsewhere.

Igitur cum patent foramina eorum et raritates harenae mixtionem in se corripiunt et ita cohaerescunt siccescendoque cum caementis coeunt et efficiunt structurarum soliditatem.


Est etiam genus pulveris, quod efficit naturaliter res admirandas. Nascitur in regionibus Baianis in agris municipiorum, quae sunt circa Vesuvium montem. Quod conmixtum cum calce et caemento non modo ceteris aedificiis praestat firmitates, sed etiam moles cum struuntur in mari, sub aqua solidescunt.

Now we come to the serious chapter in lime chemistry, which made possible the use of Concrete or caementum for which the Romans were famous. If the slaked lime (as above) is mixed with an activated silica in the presence of water, it will becomes silicate of lime, and as such a "hydraulic" cement which will withstand the action of water. This can be used above ground in walls and vaults but can also be used underwater if poured into forms or casings.
In modern engineering textbooks this is called pozzolana, from Lat. puteolana, since it was found at Pozzuli or Lat. Puteoli (meaning "little springs", coming out of a volcanic subsoil). Pozzolana cement was used well into the l9th century, but replaced by chemically engineered the stronger modern Portland Cement as chemists came to understand the actual chemical reactions involved.

Hoc autem fieri hac ratione videtur, quod sub his montibus et terrae ferventes sunt et fontes crebri, qui non essent si non in imo haberent aut e sulpure aut alumine aut bitumine ardentes maximos ignes. Igitur penitus ignis et flammae vapor per intervenia permanans et ardens efficit levem eam terram, et ibi quod nascitur tofus exsurgens, est sine liquore.

Ergo cum tres res consimili ratione ignis vehementia farmatae in unam pervenerint mixtionem, repente recepto liquore una cohaerescunt et celeriter umore duratae solidantur, neque eas fluctus neque vis aquae potest dissolvere.

This is clearly described here, a true hydraulic cement, succinctly put. Now he goes on to describe locations where this volcanically burnt silicaceous ash can be found:

Ardores autem esse in his locis etiam haec res potest indicare, quod in montibus Cumanorum Baianis sunt loca sudationibus excavata, in quibus vapor fervidus ab imo nascens ignis vehementia perforat eam terram per eamque manando in his locis oritur et ita sudationum egregias efficit utilitates.

Non minus etiam memorentur antiquitus crevisse ardores et abundavisse sub Vesuvio monte et inde envomuisse circa agros flammam. Ideoque tunc quae spongia sive pumex Pompeianus vocatur excocto ex alio genere lapidis in hanc redacta esse videtur generis qualitatem.

He calls this "spongey stone" since it is so light and porous. The whole of Roman concrete industry is based on the availability of this natural pozzolana ash from previous volcanic action, and he goes on to describe regions where this can be mined effectively. Having limestone, available through the Appenine range, and siliceous volcanic ash easily available, the Roman could think of constructions which earlier people had never been able to imagine.
Horace writing in the same period, mentions sea fish shocked at the enormous underwater dock foundations being poured everywhere. Odes III 1.33 "contracta pisces aequora sentiunt iactis in altum molibus". This expanding use of concrete was the new thecnology of that century.


He has been talking about various details throughout a Roman house, now turns to certain "apartments" where wall painting is commonly used.

Ceteris conclavibus, id est vernis, autumnalibus, aestivis, etiam atriis et peristylis, constitutae sunt ab antiquis ex certis rebus certae rationes picturarum. Namque pictura imago fit eius, quod est seu potest esse, uti homines, aedificia, naves, reliquarumque rerum, e quibus finitis certisque corporibus figurata similitudine sumuntur exempla.

Ex eo antiqui, qui initia expolitionibus instituerunt, imitati sunt primum crustarum marmorearum varietates et conlocationes, deinde coronarum, filicularum, cuneorum inter se varias distributiones. From this departure (eo) early workers made designs drawn from marble figurings, etc. In other words, abstract designs from natural veining of marble used in wall covering.

Postea ingressi sunt, ut etiam aedificiorum figuras, columnarum et fastigiorum eminentes proiecturas imitarentur, patentibus autem locis, uti exhedris, propter amplitudines parietum scaenarum frontes tragico more aut comico seu satyrico designarent, ambulationibus vero propter spatia longitudinis varietatibus topiorum ornarent a certis locorum proprietatibus imagines exprimentes.

This went on to architectural representations and then ideas drawn from the Greek theater, comic and tragic figures. Finally gardening effects (topia neut. pl.) on long interior walls, to bring the outside into the room.

pinguntur enim portus, promunturia, litora, flumina, fontes, euripi, fana, luci, montes, pecora, pastores. Nonnulli locis item signorum melographiam habentes deorum simulacra seu fabularum dispositas explicationes, non minus troianas pugnas seu Ulixes errationes per topia, ceteraque, quae sunt eorum similibus rationibus ab rerum natura procreata.,/p.

Finally all sorts of scenes from harbors to farm and country snapshots, mythological portrayals and the Trojan War. By this time you realize this is a mish-mash of the very worst taste, but just what Trimalchio points out with pride in the bourgeois Cena --- a self portrait included.

Sed haec, quae ex veris rebus exempla sumebantur, nunc iniquis moribus inprobantur. Nam pinguntur tectoriis monstra potius quam ex rebus finitis imagines certae: pro columnis enim struuntur calami striati, pro fastigiis appagineculi cum crispis foliis et volutis, item candelabra aedicularum sustinentia figuras, supra fastigia eorum surgentes ex radicibus cum volutis teneri plures habentes in se sine ratione sedentia sigilla, non minus coliculi dimidiata habentes sigilla alia humanis alia bestiarum capitibus.

Bad taste (mores) as he realizes, sheer grotesqueries. But what bother the practical Vitruvius most is the non-reality of these paintings, monsters that never existed, and especially heavy objects held up by thin stalks etc. Vitruvius is a practical man and wants things "real" as they are in life, none of this imagination paintery!

Haec autem nec sunt nec fieri possunt nec fuerunt. Ergo ita novi mores coegerunt, uti inertiae mali iudices convincerent artium virtutes: quemadmodum enim potest calamus vere sustinere tectum aut candelabrum ornamenta fastigii, seu coliculus tam tenuis et mollis sustinere sedens sigillum, aut de radicibus et coliculis ex parte flores dimidiataque sibilla procreari?

Horace in the Ars Poetica has the same Roman view of "reality in art", asking if you could suppress a laugh when viewing things like:
Humano capiti ceruicem pictor equinam
iungere si uelit et uarias inducere plumas
undique collatis membris, ut turpiter atrum
desinat in piscem mulier formosa superne,
spectatum admissi, risum teneatis, amici?
Romans are much more comfortable with the world as it actually appears to their eyes, as are many in our world who deride Modern Art, from Picasso to the inner city graffiti of the populace. Photography is bettr, it does not lie!

At haec falsa videntes homines non reprehendunt sed delectantur, neque animadvertunt, si quid eorum fieri potest necne. Iudiciis autem infirmis obscuratae mentes non valent probare, quod potest esse cum auctoritate et ratione decoris. Neque enim picturae probari debent, quae non sunt similes veritati, nec, si factae sunt elegantes ab arte, ideo de his statim debet 'recte' iudicari, nisi, argumentationes certas rationes habuerint sine offensionibus

Even when such paintings are done with fine and elegant technique, they can't be approved unless obeying the Rules (rationes) of ART. That gets rid of Dali explicitly, along with the rest of the modern trash. Maplethorpe?<
We have more on Art Criticism at the beginning of the Cena of Petronius. There it is the cheap Egyptian School which has ruined Classic Art.

William Harris
Prof. Em. Middlebury College