Copyright
aîné (Jacques-Eugène) Armengaud.

The practical draughtsman's book of industrial design : forming a complete course of mechanical, engineering, and architectural drawing online

. (page 1 of 41)
Online Libraryaîné (Jacques-Eugène) ArmengaudThe practical draughtsman's book of industrial design : forming a complete course of mechanical, engineering, and architectural drawing → online text (page 1 of 41)
Font size
QR-code for this ebook


Digitized by the Internet Archive

in 2010 with funding from

NCSU Libraries



http://www.archive.org/details/practicaldraughtOOarme



THE



PRACTICAL DRAUGHTSMAN'S



BOOK OF INDUSTRIAL DESIGN:



FORMING A COMPLETE COURSE OP



ccjmnintl, (foghumitg, anfo ^rtjritcctoal glraluhig.



TRANSLATED FROM THE FRENCH OP

M. AKMENGAUD, AlNE,

PROFESSOR OF DESIGN IN THE CONSERVATOIRE DES ARTS ET METIERS, PARIS,

AND

MM. ARMENGAUD, JEUNE, AND AMOUEOUX,

CIVIL ENGINEERS.



REWRITTEN AND ARRANGED, TOH ADDITIONAL MATTER AND PLATES, SELECTIONS FROM AND EXAMPLES OF
THE MOST USEFUL AND GENERALLY EMPLOYED MECHANISM OF THE DAY.



WILLIAM JOHNSON, Assoc. Inst., C.E.,

EDITOR OF "THE PRACTICAL MECHANIC'S JOURNAL."



"The Philosopheb may very justly be delighted with the extent of his views, and the AimFiczE with the readiness of his hands : bat let the one
remember, that without Mechanical performances, refined speculation is an empty dream; and the other, that without Theoeetical reasoning,
dexterity is little more than a brute instinct." — Johnson.

" The weakness of Accident is strong, where the strength of Design is weak."— Tapper.



LONDON:
LONGMAN, BROWN, GREEN, AND LONGMANS.

1853.



PREFACE.



Industrial Design is destined to become a universal language; for in our material age of rapid transition from abstract,
to applied, Science — in the midst of our extraordinary tendency towards the perfection of the means of conversion, or
manufacturing production — it must soon pass current in every land. It is, indeed, the medium between Thought and
Execution ; by it alone can the genius of Conception convey its meaning to the skill which executes — or suggestive
ideas become living, practical realities. It is emphatically the exponent of the projected works of the Practical
Engineer, the Manufacturer, and the Builder ; and by its aid only, is the Inventor enabled to express his views before
he attempts to realise them.

Boyle has remarked, in his early times, that the excellence of manufactures, and the facility of labour, would be
much promoted, if the various expedients and contrivances which lie concealed in private hands, were, by reciprocal
communications, made generally known ; for there are few operations that are not performed by one or other with
some peculiar advantages, which, though singly of little importance, would, by conjunction and concurrence, open new
inlets to knowledge, and give new powers to diligence ; and Herschel, in our own days, has told us that, next to the
establishment of scientific institutions, nothing has exercised so powerful an influence on the progress of modern
science, as the publication of scientific periodicals, in directing the course of general observation, and holding conspi-
cuously forward models for emulative imitation. Yet, without the aid of Drawing, how can this desired reciprocity
of information be attained; or how would our scientific literature fulfil its purpose, if denied the benefit of the graphic
labours of the Draughtsman ? Our verbal interchanges would, in truth, be vague and barren details, and our printed
knowledge, misty and unconvincing.

Independently of its utility as a precise art, Drawing really interests the student, whilst it instructs him. It
instils sound and accurate ideas into his mind, and develops his intellectual powers in compelling him to observe — as
if the objects he delineates were really before his eyes. Besides, he always does that the best, which he best under-
stands ; and in this respect, the art of Drawing operates as a powerful stimulant to progress, in continually yielding
new and varied results.

A chance sketch — a rude combination of carelessly considered pencillings — the jotted memoranda of a contem-
plative brain, prying into the corners of contrivance — often form the nucleus of a splendid invention. An idea thus pre-
served at the moment of its birth, may become of incalculable value, when rescued from the desultory train of fancy,
and treated as the sober offspring of reason. In nice gradations, it receives the refining touches of leisure— becoming,
first, a finished sketch, — then a drawing by the practised hand — so that many minds may find easy access to it, for their
joint counsellings to improvement — until it finally emerges from the workshop, as a practical triumph of mechanical
invention — an illustrious example of a happy combination opportunely noticed. Yet many ingenious men are barely
able even to start this train of production, purely from inability to adequately delineate their early conceptions, or



It PRE]

tarnish that tnnscript of their minds which might make tlirir thonghts immortal. I

only in mitigating this evil, it will not entirely fail in il I it will at least add ■ I the [adds of

Intelligence, and fom a few more approach lot Perfection —

i luut not lo«t an hoar whereof there ii a It
A written thought at midnight will redeem the livelong day."

. of Industrial 1' ngn is really as indispensably neoeesary a-* the ordinary rudiments of leamii
• form an • - .-utial baton in the education of young persons for whatever profession or employment they may
intend I the great business of th.ir lives ; for without ■ knowledge of Drawing, no scientific work, whether

relating to Mechanics, Agriculture, or Manufactures, can 1"- advantageously studied. This is now beginning to
acknowledgment, and the routi y in all varieties of educational establishments are being benefited by the

introduction of the art.

The special mission of the /'>■■ ■'<■<' Draughtsman's Book of Industrial Design may almost be gathered 1
fide-page. It is intended to tarnish gradually developed lessons in Geometrical Drawing, applied directly to the
various branches of the Industrial Arts: comprehending Linear Design proper; Isometrical Perspective, or th<
of Projections; the Drawing of Toothed W heels and Eccentrics ; with Shadowing and Colouring ; Oblique Projections;
and tin Btudy of parallel and exact Perspective ; each division being accompanied by Bpecial applications to the

litecture, Foundry-Works, Carpentry, Joinery, Metal Manufactures generally,
Hydraulics, the construction of Steam Engines, and Mill-Work. In its compilation, the feeble attraction generally
offered to student- in elementary form has been carefully considered ; and after « very gi ometrical problem, a practical
example of its application lias been added, to facilitate its comprehension and increase its value.

The work is comprised within nine division-, approprated to the different branches of Industrial Design. The
first, which ooncenm Linear Drawing only, treats particularly of straight lines — of circles — and their application to the
delineation of Mouldings, Ceilin . Floors, Balconies, Cuspids, Rosettes, and other forms, to accustom the student to
the proper use of the Square, Angle, and Compasses. In addition to this, it affords examples of different methods <.<(
constructing plain curves, such as are of frequent occurrence in the arts, and in mechanical combinations
ellipse, the oval, the parabola, and the volute; and certain figures, accurately shaded, to represent reliefs, exemplifying

casca when these Curves are employed.

The second division illustrates the geometrical representation of objects, or the study of projections. This forms
of all descriptive geometry, practically considered. It Bhows that a Bingle figure is insufficient for the deter-
mination of all the outlines and dimensions of a given subject; hut that two projections, and one or more sections,
are alu ry lor the due interpretation of interna] tonus.

The third division points out the conventional colours and tints f.r the expression of the sectional details of ol
according to their nature ; furnishing, at the same time, simple and easy examples which may at once interest the

pupil, and familiarise him with the use of the pencil.

In the fourth division are given drawings of \ atially valuable curves, as Helices and different kinds of

Spirals and Serpentines, with the intersection of surfaces and their development, and work-hop applications to Pipes,

' i id Cocks. This Btudy IS obviously of importance in many professions] and clearly so to Ironplatc-

and Boiler-makers, Tinmen and Coppersmiths.

The fifth division is di of carves relating to the teeth of Spur Wheel-. Screws and Recks,

and the details of the construction of their patterns. The latter branch is of peculiar importance here, inasmuch as it



PREFACE. v

has not been fully treated of in any existing work, whilst it is of the highest value to the pattern-maker, who ought
to be acquainted with the most workmanlike plan of cutting his wood, and effecting the necessary junctions, as well
as the general course to take in executing his pattern, for facilitating the moulding process.

The sixth division is, in effect, a continuation of the fifth. It comprises the theory and practice of drawing
Bevil, Conical, or Angular Wheels, with details of the construction of the wood patterns, and notices of peculiar forms
of some gearing, as well as the eccentrics employed in mechanical construction.

The seventh division comprises the studies of the shading and shadows of the principal solids — Prisms, Pyramids,
Cylinders, and Spheres, together with their applications to mechanical and architectural details, as screws, spur and
bevil wheels, coppers and furnaces, columns and entablatures. These studies naturally lead to that of colours —
single, as those of China Ink or Sepia, or varied ; also of graduated shades produced by successive flat tints, according
to one method, or by the softening manipulation of the brush, according to another.

The pupil may now undertake designs of greater complexity, leading him in the eighth division to various figures
representing combined or general elevations, as well as sections and details of various complete machines, to which
are added some geometrical drawings, explanatory of the action of the moving parts of machinery.

The ninth completes the study of Industrial Design, with oblique projections and parallels, and exact perspective.
In the study of exact perspective, special applications of its rules are made to architecture and machinery by the aid of
a perspective elevation of a corn mill supported on columns, and fitted up with all the necessary gearing. A series of
Plates, marked A, B, &c., are also interspersed throughout the work, as examples of finished drawings of machinery. The
Letterpress relating to these Plates, together with an illustrated chapter on Drawing Instruments, will form an appro-
priate Appendix to the Volume. The general explanatory text embraces not only a description of the objects and
their movements, but also tables and practical rules, more particularly those relating to the dimensions of the principal
details of machinery, as facilitating actual construction.

Such is the scope, and such are the objects, of the Practical Draughtsman's Book of Industrial Design.

Such is the course now submitted to the consideration of all who are in the slightest degree connected with the
Constructive Arts. It aims at the dissemination of those fundamental teachings which are so essentially necessary
at every stage fn the application of the forces lent to us by Nature for the conversion of her materials. For "man can
only act upon Nature, and appropriate her forces to his use, by comprehending her laws, and knowing those forces in
relative value and measure." All art is the true application of knowledge to a practical end. We have outlived the
times of random construction, and the mere heaping together of natural substances. We must now design carefully
and delineate accurately before we proceed to execute — and the quick pencil of the ready draughtsman is a proud pos-
session for our purpose. Let the youthful student think on this; and whether in the workshop of the Engineer, the
studio of the Architect, or the factory of the Manufacturer, let him remember that, to spare the blighting of his
fondest hopes, and the marring of his fairest prospects — to achieve, indeed, his higher aspirations, and verify his loftier
thoughts, which point to eminence- — he must give his days and nights, his business and his leisure, to the study of

En&ustrtal Besian.



abbreviations AND CONVENTIONAL signs.



In order to simplify the language or expression of arithmetical and geometrical operations, the following conventional signs
are used: —

-ign + signifies plus or more, and ^o or more terms to indicate addition.

Exaui'i i : 4 4- S, is 4 plus 3, that is, 4 added to 3, or 7.

■n — signifies minus or lest, and indicates subtraction.

4 — 3, is 4 minus 3, that is, 8 taken from 4, or 1.
The sign X signifies multiplied by, and, placed between two terms, indicates multiplication.

5 x 3, is 5 multiplied by 3, or 15.
i quantities are expressed by letters, the sign may be suppressed. Thus we write, indifferently—

a x b, or ab.
The sign : or (as it is more commonly used) -r, signifies divided by, and, placed between two quantities, indicates division.



Ex. j



18

12 : 4, or 12 -r 4, or T , is 12 divided by 1



The sign = signifies equals or equal to, and is placed between two expressions to indicate their equality.

l.\. : + 2 = 8, meaning, that C plus 2 is equal to 8.

The union of these signs, : :: : indicates geometrical proportion.

1 ; \ . : 2 : 3 : : 4 : C, meaning, that 2 is to 3 as 4 is to G.

The 6ign V indicates the extraction of a root ; as,

V 9 = 3, meaning, that the square root of 9 is equal to 3.
The interposition of a numeral between the opening of this sign, V, indicates the degree of the root Thus —

#21 = 3, expresses that the cube root of 27 is equal to 3.
The signs L. and y indicate ntpi iiiv.lv, smaller Uian and greater than.

3 Z. 4, = 3 smaller than 4 ; and, reciprocally, 4 "7 3, = 4 greater than 3.
Fig. signifies figure; and pL, plate.



rm'.NVII AND l.V.USH UNT.AK MEASUBE8 COMPARED.



1" I ...t.m.tr.*

10 Decimetres

: MttN
l" Dmattm

■Mm



1 Millimetre

= 1 Cenlini.tn-s

= 1 Decimetre

= 1 M

= 1 Decametre

= I Had

= 1 Kilometre

= 1 Mjriamitre



:
:



Kntflih.

'0394 Inches.
•SI 17 "

80.171 "

1-0936 Yards.

l'988i Poles or Rods.
19-8844
49-7109 Furlongs.

62 1 89 Miles.
621380 "



F.nftlfh.



11 Inches
3 Feet
6J Yanls
40 I'olca
8 Furlongs )
17C0 Yards I



I Inch


=


(25-400 Millim.tr,>.
• nUmitrv*.


1 Foot


=


3048 Decimetres


1 Yard


=


9144


1 1-. Ii Of Rod


=


■ n tth


1 Furlong


=


2-012 Decametres


1 Mil.





1-610 Hectometres.



CONTENTS.



Preface, ....
Abbreviations and Conventional signs,



CHAPTER I.
LINEAR DRAWING, 7

Definitions and Problems : Plate I.

Lines and surfaces, - - - - - ib.

Applications.

Designs for inlaid pavements, ceilings, and balconies : Plate II., 11

Sweeps, sections, and mouldings : Plate III., - - 13

Elementary Gothic forms and rosettes : Plate IV., - 14

Ovals, Ellipses, Parabolas, and Volutes : Plate V., - - 15

Rules and Practical Data.

Lines and surfaces, - - - - - 1 9



CHAPTER II.

THE STUDY OF PROJECTIONS, -

Elementary Principles: Plate VI.

Projections of a point, -

Projections of a straight line, -

Projections of a plane surface, -

Of Prisms and Other Solids: Plate VII., -

Projections of a cube : Fig. A,

Projections of a right square-based prism, or rectangular paral-
lelopiped: Fig. IS,

Projections of a quadrangular pyramid : Fig. Ig,

Projections of a right prism, par.ially nollowed, as Fig. ®,

Projections of a right cylinder : Fig. II, -

Projections of a right cone: Fig. f, -

Projections of a sphere: Fig.©, -

Of shadow lines, - - -

Projections of grooved or fluted cylinders and ratchet-wheels :
Plate VIII.,

The elements of architecture : Plate IX.,

Outline of the Tuscan order, -

Rules and Practical Data.

The measurement of solids, -



CHAPTER III.

ON COLOURING SECTIONS, WITH APPLICATIONS.

Conventional colours, _ _ _ - -

Composition or mixture of colours : Plate X.,

Continuation of the Study of Projections.

Use of sections— details of machinery : Plate XL, -
Simple applications — spindles, shafts, couplings, wooden pat-
terns : Plate XII., -
Method of constructing a wooden model or pattern of a coupling,
Elementary applications — rails and chairs for railways :
Plate XIII.,

Rules and Practical Data.
Strength of materials, -

Resistance to compression or crushing > roe, - - -

Tensional resistance, _ - - - -

Resistance to flexure, -

Resistance to torsion, - - - - -

Friction of surfaces in contact, - - - -



CHAPTER IV.

THE INTERSECTION AND DEVELOPMENT OF SURFACES,

WITH APPLICATIONS,

The Intersections of Cylinders and Cones : Plate XIV.

Pipes and boilers, - - -

Intersection of a cone with a sphere, -

Developments, - - -

Development of the cylinder, - - - -

Development of the cone, - - - - -

TnE Delineation and Development of Helices, Screws,
and Serpentines : Plate XV.

Helices, - - - -

Development of the helix, - - - - -

Screws, - - - -

Internal screws, - - -

Serpentines, - - - -

Application of the helix — the construction of a staircase:
Plate XVI., - - -









The intrncctloa of rarficM— a;

. 6fl

.

-

K - Ml -fair.

Calculation of the dlroeiui . it,.

iuImu of firegrate, -61

ueyt, ..... - i'A.

Safety-valves, ......



. i i: v

I ::, C3

. III. .ml XIX.

Will, - - - - i'A.

lit, - - - • I

External ,., . . - ib.
Extern.

\l\., - - . • ..'.

I \ . - - Hi.

..f a rack and ph. i > Will., ib.
GearnR of a wonn with a wonn-wh..| : Piga. 5 ami 6, Pi ttl

Mill, 07

Crum xix.

•• I, - i'A.

IliQg internally: Fin. .'., - C8

I*r»' :,.:.!. I'i mi. XX. , 09

The Hi i im mam uro (

1 i ■ , ■ X '. I.

SjiUr-n h.-. 1 iall.ni-, - - . . - 70

1'attcm of the pinion, - - - - - i'A.

Pattern of I) . . 71

Core moulds . . . . - i'A.

(M. I'I (.11. U I

- 7-

l.ir ami eireutn' . - 71

Bjioaiof gwiogj - - - -75

Thkfamtaf t&ataath, - - - - TA.

76

f 111.' wen, - . - . - 77

ib.

ro«, - . . . . - 78



i II Al I

rra sn ax of i bed gear.

Conical or bevil gajring, - - -
Dalgnftr apaJrof barfl-wbaalilo gaari Pi mi XXII.,

XIII. -

. \ I V.

-

'
' -

i uniform an. I |

-

-






;.lc uiachitx*.
•v, -


Calcul .',

-
-
ferm.



. v. \ II.



I A1;Y PRDJCIPL1 S "I SHADOWS,



. C\ UM.



'



SlIAl".

Priam, ......

Pyramid, -.. - -.
Truncated pyramid, .....

Qjrflnte, - - -

-
■ prim,
r,

Shadow ca»t by a prl
PrdTi in i - ..i Sll\|.I\..: I'i vri XXVII.,
Illumined .urfuec.% ...
Surf.

lttu shading, .....

; by softened v. . ....

atom i - .\ III.

Under,
■«• cast by one cylinder U|»n another, -
Sli. i l.ws of cones, - - -

H of an invert) I - -

Bhadon cad npon n • .

Applications, ......

ibi i b; Pi mi xxix.

.....

Shadows of surfaces of r. volut in, ■
ID I'm. ii. u I > v ■ v.

Pnmpa, - ....-

.......

i.'-puuirM, ......

l.ifuiiL,' and for. in^ pojn| -. -

The h ,...-.

Il_v.lt

different orifices, - - -

-
...
■ nation of the diat b u •• of a tti i thi

orili. ....

' I'llioll of the .Ii

rinine the widlh of an

.mine the .1. |,'li ,.f the outlet,

<»uilet Kith aapoal -



i ii M-n B vm.

AlTl [CATION 01 SB tDOWS TO COOTHl D Ql IB: Pi «

xx\

.
Barll

Aril i. mi. .v.. i Sum., Pi .. , , \\\|., -

t'ylin.lii, ,1 -.,11. ,re tli.

(angular threads: Kigs. 4 and 5,



100



■A.

I"7
i'A.

h>.

i
ib.

no

•A

III
111

i'A

B
IK



CONTENTS.



Triangular-threaded screw: Figs. 6, 6", 7, and 8, -
Shadows upon a round-threaded screw ; Figs. 9 and 10,
Application of Shadows to a Boiler and its Furnace:
Plate XXXII.

Shadow of the sphere : Fig. 1, -

Shadow cast upon a hollow sphere : Fig. 2, -

Applications, ______

Shading in Black — Shading in Colours: Plate XXXIII., -



rAriE
118
119



a.

122



CHAPTER IX.

THE CUTTING AND SHAPING OF MASONRY: Plate XXXIV., 123

The Marseilles arch, or arriire-voussure : Figs. 1 and 2, - ib.

Rules and Practical Data.

Hydraulic motors, - - - - - -126

Undershot water-wheels, with plane floats and a circular

channel, - - - - - - ib.

Width, - - - - a.

Diameter, - - - - - -127

Velocity, - - - - - - - ib.

Numher and capacity of the buckets, - ti.

Useful effect of the water-wheel, - ib.

Overshot water-wheels, - '- - - - - 128

"Water-wheels, with radial floats, _ - - - 129

Water-wheels, with curved buckets, - 130

Turbines, - - - - - - - ib.

Remarks on Machine Tools, - 131



CHAPTER X.

THE STUDY OF MACHINERY AND SKETCHING.

Various applications and combinations, - - - 133

The Sketching of Machinery: Plates XXXV. and XXXVI., ib.

Drilling Machine, - - - - - - ib.

Motive Machines.

Water-wheels, - - - - - -135

Construction and setting up of water-wheels, - - ib.

Delineation of water-wheels, - 13G

Design for a water-wheel, - 137

Sketch of a water-wheel, .-■-'-.- ib.

Overshot Water-Wheel: Fig. 12. - - - - ib.

Delineating, sketching, and designing overshot water-wheels, 138
Water-Pusifs : Plate XXXVII.

Geometrical delineation, - - - - ib.

Action of the pump, - 139
Steam Motors.

High-pressure expansive steam-engine: Plates XXXVIII.,

XXXIX., and XL., 141

Action of the engine, - - - - 142

Parallel motion, - - - - - ib.
Details of Construction.

Steam cylinder, - - - 143

Piston, - - _ - - - -«S.

Connecting-rod and crank, - - - - - ib.

Fly-wheel, ______ ib.

Feed-pump, - - - - - - ib.

Ball or rotating pendulum governor, - - - 114

Movements of the Distribution and Expansion Valves, ib.

Lead and lap, - - _ - - - 145
Rules and Practical Data.

Steam-engines: low pressure condensing engine without expan-
sion valve, - - - - - -146



Diameter of piston, _____ 147

Velocities, - - - - - -148

Steam-pipes and passages, - ib.

Air-pump and condenser, - - - - - ib.

Cold-water and feed-pumps, - - - - 149

High pressure expansive engines, - ib.

Medium pressure condensing and expansive steam- engine, - 151

Conical pendulum, or centrifugal governor, - - - 1 53

CHAPTER XI.
OBLIQUE PROJECTIONS.

Application of rules to the delineation of an oscillnting cylinder :

Plate XLL, - - - - - - 154

CHAPTER XII.
PARALLEL PERSPECTIVE.

Principles and applications: Plate XLII., - - 155



CHAPTER XIII.
TRUE PERSPECTIVE.

Elementary principles : Plate XLIII., ... 158
First problem — the perspective of a hollow prism : Figs. 1 and 2, ib.
Second problem — the perspective of a cylinder : Figs. 3 and 4, 159
Third problem — the perspective of a regular solid, when the
point of sight is situated in a plane passing through its axis,
and perpendicular to the plane of the picture : Figs. 5 and 6, 1G0
Fourth problem — the perspective of a bearing brass, placed

with its axis vertical : Figs. 7 and 8, - - - ib.

Fifth problem — the perspective of a stopcock with a spherical
boss : Figs. 9 and 10, - - - - - ib.

Sixth problem — the perspective of an object placed in any posi-
tion with regard to the plane of the picture: Figs. 11 and 12, 161
Applications— flour-mill driven by belts: Plates XLIV. and

XLV.
Description of the mill, - - - - - ib.

Representation of the mill in perspective, - 16."

Notes of recent improvements in flour-mills, - - 164

Schiele's mill, - ____ ib.

Mullin's " ring millstone," - 166

Barnett's millstone, - 16(1

Hastie's arrangement for driving mills, - ib.

Carrie's improvements in millstones, - ib.

Rules and Practical Data.

Work performed by various machines.

Flour-mills, - - - - - -168

Saw-mills, - - - - - - 170

Veneer sawing machines, - - - - - 171

Circular saws, - - - - - - ib.



CHAPTER XIV.

EXAMPLES OF FINISHED DRAWINGS OF MACHINERY.

Example Plate &, balance water-meter, - 172

Example Plate _., engineer's shaping machine, - - 1 74

Example Plate ©1 ©, II. express locomotive engine, - - 178

Example Plate IF, wood planing machine, - - - 180

Example Plate (£., washing machine for piece goods, - - 182

Example Plate _., power-loom, - ib.

Example Plate fl, duplex steam boiler, - 183

Example Plate -I, diicct-acting marine engines, - - 184'

CHAPTER XV.

DRAWING INSTRUMENTS, - . - - - - 185



INDEX TO THE TABLES.



rial

f.

Multiplier, foe regular poh-guas of from 8 to 12 sido>, - 19

Approximate ratios between circle* and ■quart*, M

Comparison of Continental measures with French millimetre* and

- I'l

Surfaces and volumes of regular |>oMi^n, - ■ 30



Online Libraryaîné (Jacques-Eugène) ArmengaudThe practical draughtsman's book of industrial design : forming a complete course of mechanical, engineering, and architectural drawing → online text (page 1 of 41)