Monday, January 21, 2008

The history of technical drawing

I put this paper together over the summer. Since that time it has been sitting on a laptop that is getting increasingly reliable. It's time to move it to a different--and more available--medium...

The primary reason that the recent drawing appears real or useful to modern uses is the rise of standards of technical drawing. Bachot, despite being a great engraver, had few existing conventions of technical drawing from which to draw. The history of technical drawing is rich and multi-layered; it winds from antiquity to the modern era and from industry to academia and back again. The first step on this journey of exploration is understanding the general purpose of these drawings. The next step is how technical drawing evolved.

The Purpose of Drawing

Technical drawing is more than just a means of representing an object. Peter Booker, the preeminent scholar on the history of technical drawing, notes that drawing is a fundamental concept of engineering thought:

In its narrowest sense engineering drawing is a language used for communication. However, languages in generally are not only useful for communication; they play an inherent part in our very thinking, for we tend to think in terms of the languages we know. Drawing is of this nature, and he who can draw can think of, and deal with, many things and problems which another man cannot. (p.xv)

As described by Booker, technical drawings are a tool of individual creativity. This thesis has been further extended by Ferguson, its greatest proponent. According to Ferguson (1977; 1992), drawing is a means of expressing the "mind's eye of the engineer":

It has been nonverbal thinking, by and large, that fixed the outlines and filled in the details of our material surroundings for, in their innumerable choices and decisions, technologists have determined the kind of world we live in, in a physical sense. Pyramids, cathedrals, and rockets exist not because of geometry, theory of structures, or thermodynamics, but because they were first a picture--literally a vision--in the minds of those who built them. (Ferguson, 1977, p.827)

But drawings are also much more than physical manifestations of the ideas of a designer. They also represent a control mechanism. Stephen Lubar, for example, notes that technical drawings (and associated documentation) have a role in extending the authority of the designer and in creating a control mechanism. He notes that:

technological representations [are] the consort of modern technological bureaucracy. By technological representations, I mean the plans, blueprints, gauges, rulebooks, instruction manuals, and models--the marks on paper, wood, and steel--that describe and abstract technology. Technological representations, I argue, make it easier to bring technological actions under the control of authority. (p.S54)

Lubar's argument is also extended by Bruno Latour who holds technical drawings up as a prime example of inscriptions. According to Latour, the flow and cascade of inscriptions is a crucial part of the operation of modern techno-science. Specifically, Latour articulates nine different properties of drawings:
Inscriptions are mobile...
They are immutable when they move, or at least everything is done to obtain this result...
They are made flat. There is nothing you can dominate as easily as a flat surface of a few square meters; there is nothing hidden or convoluted, no shadows, no 'double entendre.'
The scale of the inscriptions may be modified at will, without any change in their internal proportions.
They can be reproduced and spread at little cost, so that all the instants of time and all the places in space can be gathered in another time and space.
Since these inscriptions are mobile, flat, reproducible, still, and of varying scales, they can be reshuffled and recombined.
One aspect of these recombinations is that it is possible to superimpose several images of totally different origins and scales. To link geology and economics seems an impossible task, but to superimpose a geological map with the printout of the commodity market at the New York Stock Exchange requires good documentation and takes a few inches.
But one of the most important advantages is that inscriptions can, after only little cleaning up, be made part of a written text.
But the last advantage is the greatest. The two-dimensional character of inscriptions allow them to merge with geometry. (Latour, 1990, pp.43-46)

In short, drawings are both a means of channeling the creative initiative of a designer or an engineer and they are also a means of extending control. According to Latour's formulation, drawings have a variety of properties to attain this goal of control. They are immutable and, since they can be rapidly reproduced and the copies can be sent or carried to various locations, mobile. They also act in concert with other drawings to both fully articulate a technical concept and to enforce necessary control over processes of production or control.

Broadly there are two different categories of drawings. The first category includes drawings that attempt to maintain some degree of realism in representation. The second type of drawings utilize conventions to render representations that are artificial and in many ways unnatrualistic but have features that make them useful to designers and engineers. Booker (1963) describes this situation in terms of the type of problems that engineering drawing attempts to solve: "The problem in general terms is one of how to represent on paper an object which has shape in more than one‭ '‬direction‭'‬.‭ ‬There are two fundamental answers to this problem‭; ‬one is to retain the idea of true shape and exhibit the many shapes in an object by using a number of drawings of the object as seen from various directions‭; ‬the other is to keep the idea of‭ '‬one object,‭ ‬one drawing‭'‬,‭ ‬but transform its real shapes into apparent shapes.‭" (p.15) ‬Baynes and Pugh (1981) extend Booker's formulation and specifically identify five different types of drawings that are used by engineers:

Designers' Drawings: "These relate to the stage in development when the engineer is considering broad alternatives and putting forward outline schemes. They are frequently bound in notebooks kept by senior engineers and are often very individual in style." (p.14)
Project Drawings: "Like designers' drawings these show proposals in broad outline. However, they are not personalized; instead they are produced according to accepted rules and conventions, often by drawings offices in established companies." (p.14)
Production Drawings: "These are perhaps what most people think of as engineering drawings. Typically, they conform to a sequence starting with a general arrangement drawing and covering every detail of he product to be manufactured." (p.14)
Presentation and Maintenance Drawings: "Many of the finest drawings which now survive are presentation drawings, that is, drawings made of the product after it had been finished. Frequently they are the work of skilled draughtsmen, based on measurements taken by apprentices as part of their training." (p.15)
Technical Illustrations: "These are illustrations for technical or popularizing books that use the conventions of engineering drawing. In the nineteenth century, they reached a very high level of skill and presentation." (p.15)

I have established that drawings serve the important purposes of both supporting the design activities of engineers and that they can be used to extend control over processes of construction or production. Drawings attain these goals through the various attributes as described by Latour. And to fully leverage these capabilities a number of different types of drawings have emerged. The question remains: Where did these different drawing types come from? And how have they become so ubiquitous that a modern commentator could claim that Bachot's bridge drawings are naive? The rest of this chapter traces the ongoing evolution of technical drawing.
The interpretation of engineering drawings is not without its challenges. Brown (1999) notes that drawings can only be really interpreted in conjunction with other information sources such as business journals, memoirs, business records, patent information, etc. One of the most significant issues for researchers is the issue of context:

"Unlike traditional written records, however, mechanical drawings do pose some special interpretive challenges for industrial historians. In addition to the puzzle of deciphering a visual representation, the chief problem of drawings-as-sources is their anti-contextual character. Contexts give meaning to bojects, and the engineers, draftsmen, and workers who made and used drawings constantly interpreted them with a number of contexts in mind: who originated an innovation, what precedents could memory or records provide as a guide in designing that innovation, could shop floor tooling and workers make the mechanism as drawn, and so on. But those contexts never received any explicit notation on the plan. Indeed, dimensional drawings generally are mute regarding the motive behind the innovation depicted, the cost of production and the sales price, the buyer, the mechanism's qualities in service, or even whether it was built at all. Such plans shed only indirect light on a firm's internal organization and its production methods, while drawings in isolation are frustratingly mute on key issues like interactions that took place between draftsmen, foremen, and skilled workers." (p.48)

The Classic Era

The Caldean engineer Gudea produced the first known technical drawing 2130 BC. It is inscribed on a stone tablet and depicts the floor plan of a fortress. It should be noted that this drawing was created thousands of years before paper was invented (Giesecke, Spencer, & Hill, 1974). We can only assume that the Greek architects and Roman engineers created drawings.; None have survived to the present era. The great architect Vitruvius, however, declared that the “architect must be skilful with the pencil and have a knowledge of drawing so that he readily can make the drawings required to show the appearance of the work he proposes to construct.” (Vitruvius Pollio, 1692). Vitruvius specifically recommended that architects adopt three different kinds of architectural representation, or ideae. In Book I.2 of De architectura, he describes ichnographia, or the ground plan, orthographia, or the vertical frontal image, and scaenographia. The first two types of representation are still in common use with modern orthographic drawings. The third classification, however, has been interpreted in different ways. Some authors have interpreted scaenographia as section and some have interpreted it as perspective. The use of images was by no means universal or endorsed in the ancient world. Both Pliny and Galen condemned the practice. Carpo notes: "Pliny is categorical: the destiny of an image in a manuscript is unpredictable. No one can tell how the next copyist may distort it." (Carpo, 1998, p.163). The risk forseen by Pliny was not necessarily one of transmitting images directly, such as between an architect and craftsmen, but rather through the transmission over space and time as images were recopied. The loss of fidelity in copied manuscript images is a common concern.
In addition to the comments of Vitruvius, archaeologists have determined that the Romans developed many drawing and surveying instruments such as the A-level and the compass (Booker, 1963; Parsons, 1968). Although the buildings of antiquity provided much inspiration to later builders, they were built in a fundamentally different way than modern construction. The differences are primarily social rather than technical. The builders of the early cathedrals borrowed many construction techniques from the Romans but labour was structured in a different way. The buildings of the Romans were built primarily by slave labour and the construction process was administered by military might and order (Cowan, 1977; Fitchen, 1986).

Beginning in the mediaeval ages, the construction industry began to resemble modern practices: a client commissioned an architect or master mason to design and construct a building. The labour was completed by a group of professional craftsmen who had undergone an apprenticeship process. The representational practices of the building industry, however, differed vastly from modern practices.

There may be more on masons, early drafters, ship builders, etc. I may have to break this category out.

Gothic Era

The earliest cathedrals were completed largely without the help of drawings. Master masons maintained personal sketchbooks and lodge books but it is hard to imagine how these early documents could have been used for actual construction. The sketches of Villard de Honnecourt dating from about 1040 CE, for example, demonstrate none of the features that we now commonly associate with technical drawings. The sketches seem partial and lack explicit orthographic views or dimensions. Instead, the sketches demonstrate a range of ephemera from the world of cathedral construction such as sketches of rose windows, partial elevations of existing cathedrals, concept sketches for statues and pulpits, and sequential vignettes demonstrating common building techniques. Although Villard de Honnecourt spoke French, his sketches are annotated in Latin. It should be noted that most masons lacked formal education or advanced linguistic ability so the annotations may have served a different purpose or audience (see discussion and sketch reproductions in Bucher, 1979).

Instead of dimensioned drawings the medieval architects and draftsmen relied on a different set of local conventions that Turnbull (2000) describes as "talk, tradition, and templates." (p.55) What the masons required was not detailed drawings but rather a means of distributing knowledge both within a specific construction site and between sites. As a result they developed a rigorous guild system that served not only to protect craft knowledge but protect and distribute it. They also developed geometrical techniques that could be learned by rote and be used to develop vaults and other structural forms using simple Euclidean shapes (Shelby, 1964; 1972).

Villard's drawings conformed to an earlier form of representation. They are more gothic iconic than modern mechanical. McGee (2004) notes that these icons serve an important purpose. They fulfill the Latourian ideal of transportability but they are also necessarily mutable to support the customizations and modifications that were the reality of medieval construction.
Medieval drawings of machines and building designs also had another function. A book of siege engine designs created by the court surgeon Guido da Vigevano in 1335 reveals the importance of these early drawings as a tool for attracting patronage. This feature of drawings hasn't disappeared. Baynes and Pugh (1981) trace how early industrial magnates like James Watt used presentation drawings in a very similar manner. Henderson (1999) observed a similar role in modern engineering practices. She refers to drawings as "conscription devices" (see Fujimara, 1992, for a similar account).

The masons who actually constructed the cathedrals had their own documentary conventions. Since there were no common dimensioning practices, the design drawings of the masons were highly abstract geometrical shapes that could be used to lay out ceiling arches and groins. The shapes were based primarily on the elaborate transformation and rotation of some base shapes such as the square. In practice, shapes were transcribed from either lodge books or memory onto a sketching floor where they could be geometrically scaled to the appropriate size for the cathedral under construction (see discussion in Bucher, 1979). The drawings themselves, however, contain no annotations and are exceedingly difficult to interpret. In the fifteenth century lodge book of Master Mason “WG”, for example, the abstract geometrical figures lack annotations and dimensioning marks (see sketch reproductions in Bucher, 1979). We can only assume that masons learned to use these documents through a socialization process.

The study of mediaeval drawings is complicated for a number of reasons, one of which is that there are so few are left. This absence has two explanations (Harvey, 1972). The first explanation concerns the ephemeral nature of architectural drawings. The value of building arguably lies in the building itself rather than the documents that were used to construct it. Many intact drawings survived because they were completely forgotten in an obscure location rather than through any sort of veneration. Other drawing fragments exist because the initial heavy parchment documents were cut up and used to bind other texts. The second explanation concerns the content of the documents. The secrecy of the masons is well known and it is not unlikely that they destroyed documents that could lead to an erosion of their craft. In one extreme case, a mason reportedly killed a bishop who had learned the secret of waterproofing foundations! (Harvey, 1972)

An additional problem stems from our ability, or rather inability, to understand period drawings. According to McGee (2004), this set of problems "is of our own making,‭ ‬beginning with our Platonic approach to design, where design is taken to be a more or less entirely cognitive affair that is concerned exclusively with the conception of form. Our tendency is to take drawings as expressions of ideas, then move backwards from the drawings into the minds of artists, either to describe what they were thinking, or, since knowing what they were thinking is almost impossible, to characterize their mentality, or to opine about cognition. This to lead from the methodological frying pan into the fire, jumping from evidence we do not understand very well into the even more treacherous realms of psychology—perhaps even to celebrate 'tacit knowledge,' or 'nonverbal thinking'—long before we have really come to grips with the evidence at hand." (p.53) This determinism skews the researcher's ability to appropriately understand or to interpret historical drawings. Earlier commentators on the theatrum macharum, for example, perhaps condemned the designs for being naive when they were, as noted by McGee, "the drawings we see were considered by their authors to be perfectly adequate to the process of completing a design." (p.55-56)

One the earliest technical drawings we have was created by a woman (Ceccarelli & Cigola, 2001). The Greeks had very likely created some sort of technical drawing and the frescoes of the Romans demonstrate that they were certainly capable of creating drawings, but the medieval vicissitudes halted the train of transmission. Instead, we have one drawing of two women grinding grain at a mill. This drawing is contained in the Hortus Deliciarum an illustrated medieval work that was a large compendium of (primarily biblical) knowledge. The work was commissioned and probably executed by the Abbess, Herrad von Landsberg (1979). The drawing is notable because it is atypical for the work as a whole. Other than a depiction of two men plowing a field, a map of Stuttgart, and a depiction of various types of shoes, the rest of this substantial book is dedicated to illustrating theological topics.

To say that we actually have these drawings is a bit of a mistake. The original manuscript was burned when Stuttgart was bombed in 1870. Instead of the originals we have copies from two different researchers. I am a bit loath to credit these copies as completely faithful. Ferguson (1992), for example, demonstrates how copies of Francesco di Giorgio Martini's drawings were corrupted due to the limited technical understanding of the copyists. Similarly, Chinese copies of Besson and Ramelli are notoriously corrupt (Edgerton, xxx). At the very least, we can assume that since the copies of the Abbess's efforts were executed in the nineteenth century, the copyists could understand both the technical operation of a medieval mill and the rather unique approach to perspective.

Herrad used the drawing in question to illustrate Christ's comments on servants, particularly Luke 17:35 and Matthew 24:41:

From Matthew 24 (I've used my personal favourite: the KJV. The Abbess, of course, would have used a different version!):
36 But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only.
37 But as the days of Noah were, so shall also the coming of the Son of man be.
38 For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noah entered into the ark,
39 and knew not until the flood came, and took them all away; so shall also the coming of the Son of man be.
40 Then shall two be in the field; the one shall be taken, and the other left.
41 Two women shall be grinding at the mill; the one shall be taken, and the other left.
42 Watch therefore; for ye know not what hour your Lord doth come.
43 But know this, that if the goodman of the house had known in what watch the thief would come, he would have watched, and would not have suffered his house to be broken up.
44 Therefore be ye also ready: for in such an hour as ye think not the Son of man cometh.

And from Luke 17:
33 Whosoever shall seek to save his life shall lose it; and whosoever shall lose his life shall preserve it. Mt. 10.39 ; 16.25 · Mk. 8.35 · Lk. 9.24 · Joh. 12.25
34 I tell you, in that night there shall be two men in one bed; the one shall be taken, and the other shall be left.
35 Two women shall be grinding together; the one shall be taken, and the other left.
36 Two men shall be in the field; the one shall be taken, and the other left.
37 And they answered and said unto him, Where, Lord? And he said unto them, Wheresoever the body is, thither will the eagles be gathered together.

In addition to these early examples of technical drawing there was also a tradition of books created by craftsmen and artisans (Leng, 2004). One of the most remarkable traditions of this practice is represented in the books of the fifteenth century gun makers. The introduction of gun powder fundamentally changed the nature of European warfare and triggered a new wave fortification design. Great figures of the Renaissance such as Michaelangelo, Leonardo da Vinci, and Albrecht Durer also practiced as fortification engineers. This technological upheaval also introduced a new type of artisan: the gun maker. Most trades relied on oral tradition to transmit trade secrets but the work of the gun maker was very different from that of a mason or craftsman. They had to travel constantly to military engagements and their line of business was exceptionally dangerous. Leng (2004) notes that "military technology was developing quickly,‭ ‬instructions for the production of powder and additional substances became increasingly complicated, and their number was increasing. Master gun-makers were no longer able to memorize those instructions." (p.89) They had to turn to a tradition of documentation to capture and transmit designs. In general, the technical representations lacked the refinement of those that were to appear in the Renaissance, but a new "grammar" of drawings and conventions of technical representation began to appear.

Show the whole device; don’t annoy your beholder by using settings—he is as skilled as you and will recognize the purpose.
Use as many viewpoints as necessary to show all important parts and functions.
3. (Seldom used): Only in case of unbearable overlapping, leave out some parts and show them separately. (Leng, 2004, p.104)

As the creative demands of these artisans began to grow a new set of much more complicated rules emerged that were to establish a base line of practice for subsequent Renaissance and print-based practices:
Draw simply but in a concentrated manner.‭ ‬Try hard to manage with one sheet of paper for each device,‭ ‬but avoid mere hints that might possibly confuse a less skilled beholder.‭ ‬Therefore draw all particular details distinctly‭; ‬if necessary,‭ ‬enlarge items that might help to understand the function.‭ ‬Spare your distant colleague’s having to work out his own solutions for a result you have already achieved.‭
Do without multiple viewpoints,‭ ‬but pay extreme attention to the one you ultimately choose.‭ ‬Move laterally and upward until the maximum is visible and be a minimum concealed.‭
If elements decisive for the function cannot be shown in a general view,‭ ‬then separate them from the context.‭ ‬Draw them enlarged next to their correct position.‭ ‬Form a pictorial‭ “‬subordinate clause‭” ‬and join it with a‭ “‬conjunction‭” ‬in the form of notes or lines to the‭ “‬main clause.‭” ‬If such a separately rendered part or mechanism is applied in several sketches,‭ ‬a brief indication will suffice in the following pages.‭
If the machine is so complicated that too many parts will remain hidden and too many necessary pictorial‭ “‬subordinate clauses‭” ‬will obscure the whole context,‭ ‬then restructure‭ “‬the text‭”‬.‭ ‬Make a series of new‭ “‬main clauses‭”‬.‭ ‬Show all parts separately and connect them again by adding a general view in order to enable the beholder to discern their relationship.‭
If you are dealing with such an extended ensemble of mechanisms and machines that all single elements would result in a unfathomable puzzle of sketches,‭ ‬then exploit all your pictorial resources of analysis,‭ ‬segmentation,‭ ‬and structuring.‭ ‬Form a‭ “‬text.‭” ‬Tell a story.‭ ‬Present a general view as introduction and orientation.‭ ‬Then hold on to sequences of shafts,‭ ‬forces,‭ ‬and function.‭ ‬There you may fix‭ ‬other‭ “‬subordinate clauses‭” ‬until the whole pictorial‭ “‬text‭” ‬fits together seamlessly in your beholder’s mind. (Leng, 2004, pp.104-105)

The Renaissance

The period between 1450 and 1750 was remarkably stable in terms of graphic representation (McGee, 2004). The nature of technical drawing began to change during the Renaissance. Paolo Uccello's rediscovery of perspective is evident in Renaissance technical drawing. Whereas de Honnecourt depicted siege machines and statues as line drawings in two dimensions, Mariano di Taccola’s drawings from the early fifteenth century show the use of perspective to accurately portray inventions and machines (discussion in Ferguson, 1977; drawings in Taccola, 1969). Taccola clearly used drawing conventions not as a means of documenting existing machines and inventions but as a way of iterating through design possibilities on paper. His design techniques differed from the earlier examples of Villard, the Abbess von Landsberg, or Guido da Vigevano through the use of perspective, volume, and shading. The techniques pioneered by Taccola were to be fully exploited by later authors. McGee (2004) notes: "Taccola’s search for a means to satisfy the visual needs of his patrons had a momentous,‭ ‬but unexpected result—a graphic technique for investigation and invention that was soon, in the hands of Francesco di Georgio Martini, Leonardo da Vinci, and others, to become crucial to the development of mechanical technology in the West." (p.82) Taccola was not, however, a craftsman. While he envisioned devices of great ingenuity, the true mechanical experts were the craftsmen who were left with the task of choosing materials, dimensioning, and actual construction.

The first evidence of the features found in modern technical drawings such as exploded views, assembly drawings, and detailed cutaways comes from Leonardo da Vinci’s copious sketch books created at the very beginning of the sixteenth century. Even Leonardo drew on the work of earlier authors for inspiration, particularly Francesco di Giorgio Martini (Long, 2004). Francesco is notable is that he is more than simply a designer of machines. In his treatises he also describes the hardships of being a practitioner, including the theft of designs and a patrons over reliance on simply the paper plans rather than the expertise of the engineer. Other features of modern technical drawings such as projected views are present in works by Leonardo’s German contemporary: Albrecht Dürer (Ferguson, 1977, 1992). Despite the beauty and technical acumen demonstrated in the drawings and etchings of Leonardo and Dürer, they still lack some crucial features such as dimensioning and tolerancing. Indeed, Dürer explained that the actual construction of structures required two things: a wooden model which enabled the workers to visualize the structure in three dimensions and the use of a working drawing or tracing floor where designs could be transcribed at a 1:1 scale (Camerota, 2004).

The rediscovery of the work of Vitruvius, combined with that of linear perspective, was also important for the development of Renaissance technical drawing. Of particular importance were the three representation views: ichnographia (ground plan), orthographia, (vertical frontal image), and scaenographia (either section or perspective). The use of perspective for architectural drawing, however, was frowned upon during the Renaissance. Baldassare Castiglione and Raphael wrote to Pope Leo X around 1519 and noted that plan, elevation, and section are far more important than perpsective when creating illustrations of ancient ruins. Furthermore, Alberti, the first Western author since Vitruvius to create a work on architecture, specifically warned against perspective and the temptation of "painterly techniques":

"the allurement of painting is the mark of no architect intent on conveying the facts; rather it is that of a conceited one, striving to attract and seduce the eye of the beholder... The difference between the drawings of the painter and those of the architect is this: the former takes pains to emphasize the relief of objects in paintings with shaiding and diminishing lines and angles; the architect rejects shading, but takes his projections from the ground plan and, without altering the lines and by maintaining the true angles, reveals the extent and shape of elevation and side--he is one who desires his work to be judged not by deceptive appearances but according to certain calculated standards." (cited in Travenor, 2003, p.144)

The documents that we now recognize as Renaissance engineering drawings served a variety of different purposes in the Renaissance world. The lavishly illustrated machine books, for example, served a very different purpose than the collections of sketches created by early technical cartels like the Sangallo family. Popplow (2004) recognized four different contexts of usage: "First,‭ ‬they served to present devices to a broader public‭; ‬second,‭ ‬they could take on a role in the concrete manufacturing process‭; ‬and third,‭ ‬they could constitute part of an engineer’s personal archives.‭ ‬Fourth,‭ ‬and this final group to some extent amounts to a special case,‭ ‬engineering drawings could merge into or be connected with considerations of a more theoretical nature." ‭ (p.‬20)

Drawings represented technical drawings to a wider audience through copying. The early manuscript works of authors like Konrad Kyeser, Taccola, and di Geiorgio Martini were extensively copied (xxx Lamberini). This tradition continued into the era of the machine books. The work of Zeising, for example, is a simply a compendium of the designs of earlier authors. Both the manuscript and printed sources also served to bring the discoveries of the ancient and Arab worlds to a new audience.

The printed works also served another purpose. They enabled the technical expert to differentiate himself from both common artisans and courtier dilettantes. And they served as a personal knowledge store for the engineer in a tradition that dated back at least to Villard. These personal sketchbooks were not replaced by printed works. The sixteenth century engineer Heinrich Schickhardt, for example, copied designs from Agricola's De Re Metallica into his sketchbook, even though he owned a printed copy of the work! (Popplow, 2004) And finally, the drawings enabled engineers to work out theoretical problems. This trend is most evident in the work of Leonardo and Taccola and presaged the graphical problem solving techniques of both mathematicians and mechanicians.

It was during the Renaissance that formal training in drawing techniques was initiated. Venice's Accademia del Disegno was established in 1543as a way of training painters, sculptors, and architects in standard practices. The Accademia stood in marked contrast to the then-dominant closed training of the guilds (Henninger-Voss, 2004). But the emergent free profession of engineering had to overcome generations of bias against the mechanical arts. Hugh of Saint Victor's Didascalion of 1141, for example, clearly articulates four domains of knowledge: the theoretical, the practical, the mechanical, and the logical. The bias against the mechanical stems from the ancient Greek distinction between the aristocratic praxis, learned episteme, and base techne (Long, 2001).The struggle for many designers of machines and buildings--the mechanical--was to reposition their trade within the theoretical by adopting and instituting mathematical practices. As noted by Wilkinson (1988), by "the mid-fifteenth century, when Alberti was writing, the stain of the mechanical was so dominating that no discipline wanted to be a mechanical art." (p.474)

By adopting the rigour and techniques of mathematics, designers adopted a new mantle of authority. Perhaps the first vector they exploited with mathematics was measurement. While dimensions were still left off many mechanical designs, engineers quickly fulfilled the tasks of land surveying, important for both military and civil purposes. They also began to exploit the techniques of Euclidean geometry to create scaled representations of both civil building and fortifications. As Latour and Lubar have indicated for drawings in general, mathematics provided an effective means of control. Henninger-Voss notes: ‭"‬Measured design was the bond between the experience of the engineer and his pretensions to science. It was also the chain of good faith that bound the lieutenants, commanders, junior and senior engineers, and the counsels of government. It was the means by which decisions that could affect the lives of hundreds of men, or thousands of people, could be made at a distance of hundreds of miles. It is not coincidence that military engineers tried to impress on their patrons the epistemological foundation of their practice—not merely for rhetorical effect, but often in conscientious earnestness." (p.155)
Architectural drawings began to conform with their modern appearance during the Renaissance. Of particular importance to architects was the rediscovery of the architectural works of Vitruvius.

From Enlightenment to the Industrial Revolution

The engineering drawings of the Renaissance were influenced primarily by artistic rather than technical conventions. This situation began to change during the enlightenment. Gerard Desargues drew on the work of Maralois to develop a system of descriptive geometry that served to mathematically describe things in three dimensions (Booker, 1963). Desargues drew on a diverse range of influences including sun dialing and stone cutting.

While Desargues made important contributions to the field of engineering drawings its true hero is the French revolutionary Gaspard Monge. He developed a geometrical approach for determining the true shape of planes of intersection between generated forms. While Monge's approach generates images that superficially appear identical to the orthographic views promoted since antiquity by Vitruvius, his technique enables designers to generate proportional views from any angle or direction given the base set of orthographic views. This method was formalized in Monge's Géométrie descriptive of 1795. The primary purpose of descriptive geometry was to properly design the defilade of fortifications and to minimize the required amount of cut and fill required in their construction. While Besson and Ramelli had designed machinery that could ease the amount of manual labour required to create fortifications, Monge created an analytical method for attaining the same ends (Langins, 2004).

But Monge was far more than just a mathematical practitioner. Part of the reason for the influence of his approach was his ability to create an entire system of education that was based largely on his principles. He was actively involved in the French Revolution and was a member of the Executive Council that signed the execution order of Louis XVI (along with Antoine Lavoisier who went to the guillotine in 1794). He also worked with Carnot and others to establish the École Normale which taught practical issues such as descriptive geometry. This new French program of education was also influential as a model of technical education for the United States of America. Claude Crozet, for example, brought descriptive geometry with him when he began to teach at West Point in 1816 (Booker, 1963).

If engineering drawing is the standard language of engineers then the innovations of Monge split engineering drawing into two specific dialects (Belofsky, 1991). Engineering drawings are commonly depicted in one of two formats commonly referred to as either first angle projection and third angle projection. The root of the difference lies in how the individual orthographic views are arranged. First angle is purely Mongian in that the views are presented in the order of the surface onto which they are projected. In a drawing of a steam locomotive in first angle projection, the top view would appear below the side view. Third angle projection is more intuitive and less academic in that it presents the views in the order that a naive viewer would expect: the top view is above the side view, the left view is to the left of the side view, etc. While the academic first angle projection was widely adopted in countries such as Germany and France with academically trained engineers, it was largely ignored in the United States and, to a lesser extent, the United Kingdom where shop trained engineers still predominated.

The ongoing battle between the first and third projections really had very little impact on the shop floor. Only engineers with extensive training--either academic or in the shop--actually used drawings and would have presumably been proficient in either first or third projection. It was only in the early twentieth century that shop floor drawings were used. As noted by Mori (1992) in his response to Belofsky, "as far as common mechanics were concerned, engineering drawings were in the category of heavenly documents." (Mori & Belofsky, 1992, p.853). It was not until the introduction of blueprinting technologies that cheap copies of drawings became feasible. With blueprinting, everyone in a shop had access to drawings regardless of their education and experience so easily read drawings rendered in the third angle projection became more prevalent.

Engineering drawing emerged with the industrial revolution.

The pioneering firm of Boulton and Watt, for example, were early adopters of architectural drafting conventions for their depictions of stationary engines. Notably, the firm was responsible not just for the design of machinery but also for the substantial structures that housed these early steam engines. This dual role perhaps explains how architectural convention began to be applied to mechanical devices. As noted by Baynes and Pugh (1981): "The appearance of engineering drawings as a fully-fledge medium for communication in the engineering industry coincided neatly-almost too neatly-with the establishment by Matthew Boulton and James Watt of the first factory in the world for the construction of stationary steam engines." (p.35)
The popularity of technical drawing increased with the additional development of industry. The first iron hulled steamship, the Aaron Manby, was launched in 1822 and heralded a new era in production. The skills of the shipwright were soon to give way to those of the boiler maker.
1814: Drawing of ship shows hidden lines.

Another great influence on the propagation of the style of mechanical drafting were the plates of the Encyclopedie of Diderot and D'Alembert.

One popular technique of mechanical representation was formalized by Reverend William Farish at Cambridge in the early nineteenth century through his works on applied science. He described an axiometric drawing technique which showed objects in an artificial three dimensional space. The axes were scaled to be accurately measurable. While this technique distorted the appearance of the object it enabled the craftsmen building an object to take measurements directly from the representation. Booker (1963) explains: ‭"‬whilst multiplane orthographic views are essential for design purposes and are the only realistic way in which shape can be recorded for engineering purposes, the interpretation of such drawings, in which one object is represented by a number of pictures, is a difficult matter, sometimes even for those with considerable experience." (p.116) Farish's ideas weren't new. Leonardo had experimented with cubed representations and the concept is evident in Persian manuscripts. Camrota (2004) notes that the technique was popular in early mathematical texts and was exploited by engineers in the sixteenth century. This "soldierly perspective" satisfied the need to have a drawing that was both "pictorial" and "measurable."

The Shift to Production Control

With the general spread of knowledge during the Renaissance, technical drawings began to be used for additional purposes. Baynes and Pugh note that drawings developed considerably between 1770 and 1800. They became tools for managing production. While this use was most fully developed during the industrial revolution, it had its antecedents in earlier examples of large scale manufacture. The British Royal Navy, for example, commissioned and maintained detailed drawings of their ships from the late seventeenth century. It is unclear what purpose these drawings actually served since shipbuilding of the day still resembled the practices of the cathedral masons. Labour, for example, relied on craft knowledge and the use of full-scale drawings (or moulds) to construct the hulls of ships. Although early scientists were increasingly attempting to apply scientific method to the construction of ships, McGee (1999) notes that—given the hydrodynamic theory of the time—it would have required longer to calculate the buoyancy of a ship than to actually build it! Instead, McGee speculates that the reliance on drawings was related to extreme cost and administrative complexity of the British Navy.
The next major innovation in technical drawings appears to come from eighteenth century France where the Physiocrats began to demonstrate loudly against the power of the craft guilds (Alder, 1998). In order to break the power of the guilds that both built and sold muskets, the government essentially banned the guilds and nationalized the entire industry. In order to maintain quality, however, the military had to adopt specific techniques that enabled a market for standard muskets with interchangeable parts that could be sold as commodities. The military adopted standardized drawings and testing apparatus such as “Go Gauges” and “No Go Gauges” to ensure uniform production. The process of creating drawings was assisted immeasurably by an innovation of Gaspard Monge: descriptive geometry (Giesecke et al., 1974). Through the use of descriptive geometry, the technical drawings of the era begin to resemble modern drawings through the use of distinct “views” i.e., a plan view, an elevation, and a front view. These early modern technical drawings still lack certain features such as dimensioning possibly because standardized units of dimension were not yet commonly used. During the eighteenth century, French authorities replaced locally relevant units of measure such as the “Roman Foot” with an official Pied de Roi. The metric system was eventually adopted by France in 1795 doing away with measures related to human dimensions such as the foot or acre (the amount of land tillable by one man behind one ox in one day). It should be noted that French manufacturing improvements allowed Napoleon to field the lightest and most powerful cannons of era. The light weight and maintenance ease of these field pieces enabled Napoleon to wage the first large scale mobile modern wars (Alder, 1998).

Other notable features of these drawings include the use of shadows and shading. These features are completely superfluous for actually reproducing the artefact but reveal another purpose for drawings. In addition to being used for manufacturing, they acted as sales tools—a common feature throughout the history of modern technical drawing (Brown, 2000). Alder, however, indicates that the shading may have made drawings more accessible to lay people unversed in the mysteries of mechanical annotation and the abstractions of descriptive geometry (Alder, 1998). Given that few people had skills in numeracy or geometry (Pannabecker, 2002), these features—although omitted from drawings in the twentieth century (Brown, 2000)—were crucial to the craft labour of an earlier era.

The use of drawings for production control in the modern era is perhaps most evident in the work of William Sellers. He is most famous for creating a standard system of screw threads that was later adopted as an American standard. Sellers was also instrumental in his early support for the work of Frederick Winslow Taylor and for the use of piece rates for production, cost accounts for every machine produced, and establishing patent pickets to defend his innovations. As noted by Brown (1999), the work of Sellers demonstrates three design principles: "parts designed proportionately and without any embellishment, use of precise standards and fixed tolerances in production--all to make machines that in operation would curtail or replace costly and skilled hand labor." (p.31)

Most of the technical drawings of the time were intended to fulfill two functions. The first was to establish detailed and toleranced designs to guide production and limit the probably of production and design errors. The second function was related to the production process. Detailed designs facilitated the division of labour and the creation of the specialized processes. Sellers's greatest innovation was the creation of a drawing office that essentially operated as a center of calculation for the various innovations that occurred within his manufacturing operations. His drawing office essentially fulfilled a similar function to the personal sketch books of medieval engineers.

Brown (1999) describes the three particular roles that were fulfilled by the design drawings of Sellers: "general arrangement drawings as an aid to marketing, design plans that established a product's form, and production or shop drawings to guide workers on the factory floor." (p.34) The visual rhetoric used by Sellers's drawing office was very consistent and stable after about 1870. The modern form of engineering drawings began to surface earlier. By 1855, for example, all draftsmen demonstrated a consistent use of tints and used red ink for centre and dimension lines. Drafting emerged as a genuine career in the 1860s and it represented an important step on the promotion ladder for young and aspiring engineers. As drafting became more about engineering design and less about artistic ability both the drawings themselves and the machines they depicted changed. The elaborate tinting and shadows that had been so important in Monge's era disappeared from the drawings. Similarly, industrial machinery shed elaborate paint schemes for standard grey finishes and shed ornamental castings for functional designs. One of the last drawing elements to stabilize in Sellers' drawings was the placement of the legend. But after 1878 they always appeared in the bottom right position now familiar to most engineers. Even the content of the title block became standardized after about 1885 when Sellers adopted a standard "Dewey-decimal-like" number based on a taxonomy of machine and drawing types (Brown, 1999, p.52 n.56).

Even though engineering drawing of the era was based on Euclidean geometry, most of the men working in drawing offices were unfamiliar with formal geometry. For the most part, the rare times when they needed algebra they were able to lift the basics from various pocketbooks or vade mecum created for the purpose. Brown (1999) notes that prominent designers like Sellers occasionally used algebra as a design basis for certain compound shapes. This practice apparently emerged in the 1860s. (Note: This observation stands in marked contrast to Mahoney's comment that algebra and not geometry is the fundamental building block of modern science, but apparently not engineering.)

A recent innovation that brought technical drawings to their current form was blue printing (Brown, 2000). This cheap process of reproduction was introduced during the 1880s. Until blue printing, limited sets of drawings were created for a given project. The production of copies generally required either laborious hand tracing or expensive lithography. With the advent of blue prints, multiple copies and individual “detail” or “bench” drawings could be made for each individual component. Prior to blue prints, individual labourers were largely responsible for creating individual components and often had to make decisions regarding the dimensioning and surface finishing. This standard practice changed after the introduction of blue prints. Instead, workers were required to explicitly follow the requirements of the drawing and use only the dimensions explicitly rendered by the designer; “take-off” or inferred dimensions acquired through the use of rulers or callipers were no longer permitted. Brown (2000) notes that this transition from tacit expertise acquired through an apprenticeship to the explicit authority of detail drawings is an example of the craft labour deskilling processes evident of modern management techniques.

The colour that had been introduced into drawings by the French engineers and the British and American industrialists gradually disappeared. According to Baynes and Pugh (1981): "At the beginning of the twentieth century, colour was still in widespread use in engineering drawings. By 1914 this practice has virtually ceased. It is unlikely, therefore, that the Great War and the pressure it exerted on drawing-office staff were solely to blame. Instead, there was a change in attitude, perhaps an increasing awareness of commercial imperatives. Before it vanished, colour was being used in at least three different ways: to indicate materials; to differentiate between flows within a system; and simply as embellishment." (p.175)

Other conventions of engineering drawing have emerged. For example, standards governing the most fundamental aspect of drawing--line--were first formulated in the UK in 1885. In the USA, the first standards emerged in 1927 and were formalized in 1935 (Booker, 1963).
The craft of creating modern technical drawings comes with its requisite and esoteric equipment. There was a time when engineering students on university campuses were instantly recognizable because they carried t-squares and set squares (or triangles). While engineers have always used pencils, rules, and compasses, the adoption of this more specialized equipment was hastened by Farish's introduction of isometric (or axiometric) perspective in the nineteenth century. Baynes and Pugh (1981) cite an early drafting manual--A Manual of Machine Drawing and Design by David Allan Low and Alfred William Bevis (1902)--on the appropriate use of these instruments:
3. Tee-Squares. The most reliable form of tee-square is that in which the blade is fixed to the stock, but not sunk into it. The best squares are made of mahogany, and have the working edges of the stock and blade faced with ebony. [Our illustration] shows the most approved form of tee-square. The blade is fastened to the stock by screws, and is further secured by two 'steady pins', which fit tightly into holes through the blade and stock.
4. Set Squares. These should be made of pear-tree or vulcanite. Framed set-squares are not so liable to get out of truth as the plain wooden ones, but thy are objectionable on account of their greater thickness. The shortest edges of the set-square should not be less than 5 or 6 inches long.
5. Various Drawing Instruments. All compases should have round steel points, and, if possible, needle points. The dividers should have a screw adjustment. Small steel spring bows are very useful for bracing small circles. The drawing-pens for inking-in should have one nib hinged, so that it may be lifted for cleaning.
For mechanical drawing, pencils marked H or HH are the best, although some draughtsmen prefer even harder pencils. For freehand and rough work, or for lining in a drawing which is not to be inked-in, pencils marked HH or F are most suitable. Pencils for mechanical drawing should be sharpened with a chisel point; but for freehand drawing the point should be round. Care should be taken not to wet the point of the pencil, as the lines are then very difficult to rub out.
The drawing-paper for working drawings is generally secured to the board by drawing-pins, having steel points and brass heads with bevelled edges. The steel points should not come quite through the head. The paper for finished or pictorial drawings, or for drawings upon which there is a large amount of work, are often 'stretched' on the board-that is, it is damped and then glued or gummed at its edges to the board.
6. Scales. The scales most frequently used in machine drawing range from one inch to a foot to full size. The smaller scales are used for the general views of large machines. The working drawings of details should be to as large a scale as convenient, and if possible should be full size. The best scales are made of ivory, the next quality are made of boxwood, and the cheapest are made of thin cardboard. Cardboard scales, if properly made and varnished, do very well for ordinary drawings, and if used carefully last a long time. The divisions of the scale should be marked down to the edge of the ivory, boxwood, or cardboard so that measurements may be made by applying the scale direct to the drawing. (p.23)

Although the history of technical drawing provides some rich insights into the history of construction, production, and the interchange between social practices and explicit documents, we still lack a detailed understanding of the interchange process. There is prima facie evidence that the tacit knowledge and social practices of craft labour was eliminated through managerial deskilling. As these skills disappeared, technical drawings evolved into highly sophisticated documents. How did this transition happen? How did technical documentary practices—especially architecture—develop during this period?