The Textbook of Architecture

Regulae

The Atlas of Rules

617 rules of building, each with the book or building it comes from and a model to turn.

The Derand–Blondel rule for abutments

To find how thick the pier of an arch must be, divide the intrados into three equal parts; draw a line from the springing through the first division, and produce it beyond the springing by its own length. A vertical through the end of that line marks the outer face of the pier.

pier ≈ ¼ span (semicircle) · ≈ 0.23 span (equilateral) · less for a lancet

The pendentive: a sphere cut by a square

To set a round dome on a square bay, imagine a sphere passing through the four corners of the square; cut it by the four vertical planes of the sides and by the horizontal plane of their crowns. The four spherical triangles left in the corners are the pendentives; the circle at their top carries the dome.

sphere radius R = S⁄√2; arches = sphere ∩ side planes (radius S⁄2); ring at h₀ + S⁄2 with radius S⁄2

The parterre longer than it is wide

Make the parterre oblong rather than square, since figures somewhat oblong look better on the ground than square ones; later practice made it as broad as the front of the house and about twice as long.

parterre oblong; later practice: width ≈ house front, length ≈ 2 × width

Lawn to the door, clumps on the rises, a belt round the edge

Bring grass up to the walls of the house and keep the cattle off it with a ha-ha; plant trees in clumps on the rising ground and as single specimens on the lawn; and enclose the park with a belt of woodland, with a drive inside it from which the park is seen.

The Crystal Palace grid of 24 feet

Build on a single grid of 24 feet, set by the 8-foot spacing of the roof ridges and the size of the largest pane of glass, so that every column, girder, sash bar and pane is one of a few standard parts that can be made by machine, delivered and bolted together in any number.

pane 49 × 10 in · ridge 8 ft · bay 24 ft · spans 24, 48, 72 ft · 1,848 × 408 ft

The border planted by colour

Arrange a long border in a sequence of colours: at the ends, cool blues, whites, pale yellows and pinks with grey foliage; towards the middle, stronger yellows and oranges rising to the deepest reds at the centre; then back again. Plant in long, thin, overlapping drifts rather than blocks.

Munstead Wood main border: 200 × 14 ft · cool → warm → hot → warm → cool

Ever taller, ever narrower

Within a generation the nave vaults of the French cathedrals rose from about 37 m to 48 m while their spans stayed near 15 m: the ratio of height to width climbed from about 2.3 to over 3, until at Beauvais part of the choir vault fell.

Chartres ≈ 37 m · Reims ≈ 38 m · Amiens ≈ 42 m · Beauvais ≈ 48 m

The Doric corner conflict

A Doric frieze cannot obey all three of its rules at a corner: triglyphs over the column axes, a triglyph turning the corner, and metopes as broad as they are high. One of them must give way.

displacement of the corner triglyph = e − t⁄2 (e = half-depth of the architrave, t = triglyph width)

The door from the height of the room

Divide the height from floor to ceiling into three and a half parts and give two and a half to the opening; make a Doric door five and a half twelfths as wide as it is high (an Ionic one two-fifths), and narrow it slightly at the top.

h = 2½⁄3½ H; Doric w = 5½⁄12 h, Ionic w = h ÷ 2½; top narrowed by ⅓, ¼ or ⅛ of the jamb as h ≤ 16, ≤ 25, ≤ 30 ft

The hall, its screens passage and its two ends

Put the hall at the heart of the house and enter it at one end, by a passage running through the house from front door to back door, screened from the hall. Open the buttery, the pantry and, between them, the way to the kitchen off that passage, at the hall’s lower end; put the family’s parlour, and the great chamber over it, beyond the hall’s upper end, where the high table stands.

The family’s rooms and the servants’, kept apart

Plan the house in two departments, the family’s and the servants’, with their own rooms and passages (and, as the house grows larger, their own stairs), so that neither sees nor hears the other in the ordinary course of the day: the kitchen and its offices to one side or behind, reached by their own corridor, and nothing of the work of the house carried through the family’s rooms.

Every room to its aspect

Give each room the aspect that suits the hours it is used: the drawing room to the south-east, the morning room to the east, the library a little east of south-east, the dining room to the north or north-east, cool and out of the evening sun, and the kitchen and offices to the north; the best aspect of all is south-east, the worst south-west.

The Doric module

Divide the front of a Doric temple into modules; the column’s thickness is two modules, its height with the capital fourteen, the capital one, the architrave one, and the triglyphs one and a half high and one wide.

M = ½ D; column = 14 M; capital = 1 M; architrave = 1 M; triglyph = 1 × 1½ M; metope = 1½ × 1½ M

The Corinthian capital

The Corinthian capital is as high as the column is thick; its abacus is one seventh of that height, and the rest is divided in three: the lower leaves, the upper leaves, and the stalks from which the volutes spring.

capital = 1 D; abacus = ⅐; leaves : leaves : volutes = 1 : 1 : 1; abacus diagonal = 2 D

Mauch’s volute: each turn half the one outside it

Draw the Ionic volute seven eye-diameters high and six wide, with the eye four diameters below the top; lay three turns about centres set out in the eye so that each winding is half as wide as the one outside it and the spiral runs into the top of the eye.

height = 7 e, width = 6 e; eye centre 4 e below the top; radii from the eye centre (e = 16 parts): 60, 52, 44, 36, 30, 26, 22, 18, 15, 13, 11, 9 → 8

The golden section

To divide a line in extreme and mean ratio, make the whole stand to the larger part as the larger part to the smaller; the ratio is φ = (1 + √5)/2 ≈ 1.618. Construct the golden rectangle by swinging the line from the midpoint of a square’s side to its far corner.

φ = (1 + √5)/2 ≈ 1.618; φ² = φ + 1; 1/φ = φ − 1 ≈ 0.618

The lower dome pulls apart

Expect a hemispherical dome to be in compression along its meridians everywhere but in tension round its horizontal rings below about 52° from the crown; restrain that lower zone with weight, thickness, rings or chains, or it will crack along the meridians.

thin hemisphere under its own weight: hoop force changes sign at ≈ 51.8° from the crown

Facing and core

Build a Roman wall as two facings of brick or small stone with a core of concrete poured between them in layers; tie the facings into the core with bonding courses of large tiles laid through the whole thickness at intervals.

bonding courses of bipedales (2 ft tiles) every 1–1.5 m of height

The fall of an aqueduct

Lay the channel of an aqueduct with a steady fall of not less than a quarter of an inch in every hundred feet, cover it with a vault against the sun, and carry it through hills in tunnels and across valleys on arches.

minimum fall ≈ 1 : 4,800 (Morgan’s reading); Nîmes aqueduct: ≈ 12.6 m in ≈ 50 km ≈ 1 : 4,000

The Roman theatre: four triangles

Draw the orchestra circle and inscribe in it four equilateral triangles at equal intervals; the side nearest the scene fixes the front of the scaena, a parallel through the centre fixes the front of the stage, and the angles on the auditorium side give the directions of the stairways.

12 vertices at 30°: 7 fix the stairs of the lower cavea, 5 fix the doors and passages of the scene; stage depth = r⁄2

The scene: twice the orchestra

Make the scaena twice as long as the orchestra is wide; raise its podium a twelfth of the orchestra diameter, its lower columns a quarter, their entablature a fifth of the columns; above, a parapet half the podium and columns a quarter shorter than those below.

L = 2D; podium D⁄12; columns D⁄4; entablature ⅕ col.; upper parapet ½ podium; upper columns ¾ lower

Alae, tablinum and fauces from the atrium

Proportion the rooms round the atrium from it: the alae from its length (a third for atria of 30–40 feet, a quarter for 50–60), the tablinum from its width (two-thirds for a 20-foot atrium, half for 30–40 feet, two-fifths for 40–60), and the entrance passage from the tablinum.

alae = L⁄3 … L⁄5; tablinum = ⅔ W (20 ft), ½ W (30–40 ft), ⅖ W (40–60 ft); fauces = ⅔ or ½ tablinum

The peristyle garden

Make the peristyle a third longer across than it is deep, its columns as high as the colonnades are wide, and the spaces between them not less than three nor more than four diameters.

width = 4⁄3 depth; column height = colonnade width; intercolumniation 3–4 D

The forum basilica

Make a basilica between a third and a half as broad as it is long; make each aisle a third of the width of the central space, and the columns as high as the aisles are broad.

W = ⅓ to ½ L; aisle = ⅓ nave; column height = aisle width; upper columns ¼ smaller

The triumphal arch

Pierce a massive rectangular pier with one arch, or with a tall central arch between two lower ones; frame the openings with columns on pedestals carrying an entablature, and crown the whole with a high attic for the dedicatory inscription.

Arch of Titus: 13.5 × 15.4 m, one opening 5.4 × 8.3 m; Arch of Constantine: 25.9 × 21 m, openings 6.5 × 11.5 m and 3.4 × 7.4 m

Each covering has its lowest pitch

Pitch a roof no lower than its covering allows (roughly 45° for thatch, 35° for plain tiles, 20–25° for slate, 15–20° for interlocking tiles, a few degrees for sheet metal) and steeper where snow lies long or rain is heavy.

thatch ≥ 45° · plain tile ≥ 35° · slate ≥ 22½° · pantile ≥ 17½° · metal ≥ 5° · membrane ≈ 1–2°

The jōbō grid: blocks of forty jō

Divide the capital into blocks (machi) forty jō square; gather sixteen blocks into a ward (bō) and the wards into rows (jō); separate the blocks by lanes of four jō and the wards by avenues of eight to twelve, and make Suzaku-ōji, the central avenue, twenty-eight.

machi = 40 jō (c. 120 m) · kōji 4 jō · ōji 8–12 jō · Nijō 17 jō · Suzaku-ōji 28 jō (c. 84 m) · city 1,508 × 1,753 jō

Land in the capital by rank

Grant residential land in whole blocks and fractions of blocks according to rank: several blocks to the highest ministers, one or two to officials of high rank, and to ordinary households a half, a quarter or less, according to their size.

Minister of the Right 4 machi · high ranks 2 · middle ranks 1 · households 1, ½ or ¼ (691); in Heian-kyō, ordinary lots of 1/32 machi (c. 15 × 30 m)

Mountains behind, water before: the geomantic site

Seat the capital in a basin closed by mountains: a guardian mountain behind (north), a lower range on the left (east) as the Azure Dragon and on the right (west) as the White Tiger, a facing hill in front (south); let a stream cross the basin and a great river flow beyond.

Bugaksan (behind) · Naksan (left, Azure Dragon) · Inwangsan (right, White Tiger) · Namsan (in front) · Cheonggyecheon within, the Han River without

Twelve feet between houses

Leave at least twelve feet between a new house and its neighbour; build no balcony lower than fifteen feet from the ground or nearer than ten feet to the house opposite; do not block a neighbour’s view of the sea within a hundred feet; and keep the shops between the columns of the great porticoes small and faced with marble.

gap ≥ 12 ft (≈ 3.7 m) · balcony ≥ 15 ft up, ≥ 10 ft apart · sea view protected within 100 ft

The monastery arranged round the church

Put the church in the centre with its altar to the east; the cloister against its south side, ringed by dormitory, refectory and cellar; the abbot, the school and the guests to the north; the novices, the sick and the gardens to the east; the kitchens, workshops, mills, barns and animals to the south and west; the hospice for the poor by the entrance.

One grid for the whole island

Lay the whole island out in a single rectangular grid regardless of the ground: avenues 100 ft wide running its length, cross streets 60 ft wide across it, and blocks 200 ft deep between them, the houses to be straight-sided and right-angled because such houses are cheapest to build and most convenient to live in.

avenue 100 ft (30 m) · street 60 ft (18 m) · block 200 ft (61 m) deep, 600–900 ft long