Saturday, March 25, 2006

Hagiography: Errard de Bar-le-Duc
  • 1554. Jean Errard is born to a family of minor nobility in Bar-le-Duc, capital of the princedom of Bar which was under the rule of Lorraine.
  • 1572. He adheres to Protestantism, attending the reformed French church of Heidelberg.
  • 1573. Errard registers at the University of Heidelberg. He was probably seeking refuge since Protestantism had been proscribed in both Bar and Loraine.
  • 1580. He studies fortification in Italy and enters the service of Charles III of Loraine, to whom he dedicates his book of machines. In the early 1580s he marries Barbe de Rheims, the daughter of a local advisor.
  • 1584. Le Premier Livre des instruments mathématiques méchaniques was published in Nancy. Errard was only 30 years old at the time.
  • 1589. During the Wars of Religion, Errard sides with his faith and serves the princes of Sedan. He fortifies the town of Jametz which eventually capitulates after a prolonged seige. The success of his fortifications gives Errard a strong reputation and he is recruited by the new king, Henri IV.
  • 1591. Henri IV nominates Errard premier ingenieur and brings him into the Conseil Royal. Errard is also granted the right to mint coins.
  • 1591. Errard is at the siege of Chartres...
  • 1592. And Dreux.
  • 1594. Errard explores military issues in his second work: Géometrie et pratique général, published in Paris.
  • 1595. Errard fortifies Sedan...
  • 1597. And Montreuil-sur-mer...
  • 1598. And Amiens. His particular style of fortification is still evident in ariel photographs of the area. As an Ingeniur du Roi, Errard is accompanied by Jean Martellier, his conducteur des desseins.
  • 1598. Joseph Ballot's Modelles artifices de feu et divers instruments de guerre is published. It demonstrates the influence of Errard's work and is also quite rare (Endrei).
  • 1599. Following the treat of Vervins, Errard is elevated to the nobility and continues his work fortifying towns and strutures.
  • 1603. His services are sought by the Elector Palatine.
  • 1607. Errard's son Maximilien dies at Provence.
  • 1610. He dies at Sedan. His nephew Alex inherits his work.
Errard is now remembered for his work as a military engineer rather than his earlier work on machines. Picon holds that Errard's work on fortification, La Fortification Démonstrée, as an example of how Renaissance engineers felt the need to ground their science in practice. It remains one of the few examples of works on fortification executed by non-Italian authors (de la Croix, 1963).

Errard's work on fortifications may have been a pioneering effort but it was quickly eclipsed by later authors. Vauban was apparently the expert on fortifications. Errard's designs were viewed as deficient by later commentators. Lendy, for example, provides very explicit commentary:

"Errard de Bar-le-Duc, in 1591, gave 90-degrees to the salient angles of the bastions, made the flanks perpendicular to their faces, and transformed 2/3rds of their length into Orillons. The ditch was 26 yards wide at the shoulder and 30 at the salient.

This system, which it is impossible to apply to high polygons, is very defective.

The orillons mask the curtain, the defenses of the ditch is oblique, and the ditch itself is traced on wrong principles." (Lendy, p.169)

His work on machines and geometry also contained notable inventions. Errard, for example, was no slouch from the perspective of scientific instruments. The invention of the sector, commonly attributed to Galileo or the Englishman Thomas Hood, should actually be attributed to Errard. He provided the first representation of the device in La geometrie et practique generalle d'icelle of 1594 (williams 2003).

My primary purpose, however, is to explore Errard's book on machines. His machines are, for the most part, original. He does, however, make extensive use of Archimedes screw, which had been popularised by Cardano. He also represents a vertical-axle windmill, an idea that can be traced through the work of Gaultherius Rivius (1547) and Mariano Taccola (1438). He also demonstrates a rod-engine, something also evident in the work of Juanelo Turriano and Ramelli. A rod-engine was later put to use in the Machine de Marly.

In his depiction of a method for spinning wool (plates 25 and 29), Errard cites the original inventor (itself a remarkable thing): Charles Deruet. He was an experienced clock maker. This connection indicates the importance of automaton makers for early technicians.

Errard is also unique for his attempts to depict solid structures in addition to mechanical inventions. Unlike Besson or Ramelli, Errard provided representations of bridges and other solid structures (as did later authors such as Verantius and Leupold: Endrei).

Errard's work, of course, is but one component of the entire genre of the theatra machinarum. Endrei provides a description:

"Leaving aside any question of artistic ambition, if we look at the machine books without any such preconceptions, the are, just like the drawings of Kyeser or Leonardo, rational, expedient representations, the aim of which is to convey technical information, albeit information marked by the spirit and demands of the period. Artistic design assumes priority only exceptionally, as in the case of Besson's representation of a state coach. This we may place to the credit of his engraver, Andruet de Cerceau [sic], rather than to Jacques Besson himself.

A special group of these technical books is remarkable for full-page engravings, mostly in small folio format, accompanied by relatiely short explanations." (p.180-181)

He also makes some other interesting comments about the genre. They inherit their form from earlier works by authors like Valturio or Alberti. He also notes that later works, particulary by the likes of Leupold or de Caus, depended more on text than on illustrations. Errard's own work is notable in that it completely eschews depictions of military technology unlike, for example, Ramelli's work. This finding is somewhat surprising given that much of Errard's professional success was due to his later work on fortifications.

Picon also add some interesting comments on what's still required for the ongoing study of engineering. I need to park them somewhere:

"Engineering looks more like a continent marked by striking contrasts than like a unified field. On this continent, no self-eviden link seems to exist between the organization of the profession and the various activities engineers are involved in. In this context, it may be tempting either to define the engineer through his social identity and aspirations or to limit oneself to a relatively narrow domain of technological expertise." (Picon p.422)

"Between the formalized knowedge that can be traced through courses an treatises, and the everyday decisions made by engineers, there must be for sure some kind of intermediate know-how. This intermediate level is still to a large extent unexplored." (Picon p. 424)

"With its use of technology as an almost counter-natural power, engineering had something to do with cheating, especially in the conduct of war, contrary to the frank and open attitude of traditional chivalry. In that respect, the engineer was comparable to Ulysses, wandering in a strange and threatening world the dangers of which he had to conjure through tricks like the Trojan horse." (Picon p.430)


Buisseret, David (1968). Sully and the Growth of Centralized Government in France, 1598-1610. London : Eyre & Spottiswoode.

Croix, Horst de la (1963). The literature on fortifiation in Renaissance Italy. Technology and Culture. 4.1:30-50.

Endrei, Walter (1995). Jean Errard (1554-1610) and His Book of Machines: Le Premier Livre des instruments mathématiques méchaniques. History of Technology. 17: 179-190.

France-Lanord, Albert (1979). Introduction. In Albert France-Lanord (ed.) Le premier livre des instruments mathematiques mechaniques. Paris : Berger-Levrault.

Lendy, A.F. (1857). Elements of Fortification: Field and Permanent. For the use of students, civilian and military. London : John W. Parker and Son.

Picon, Antoine (2004). Engineers and engineering history: Problems and perspectives. History and Technology. 20.4:241-436.

Williams, Michael R. and Erwin Tomash (2003). The sector: Its history, scales, and uses. IEEE Annals of the History of Computing. 25.1: 34-47.

UPDATE December 31, 2006

Langins provides some additional details on Errard on his work on the life of Vauban:

  • Errard was the first French author of a work on fortifications. Dedicated to Henry IV, his work seems to discount his earlier work on machines: “Discourses on mechanical things do not merit this title [of science] at all. There is no question here [in my treatise]... about sketches that might work for someone by chance, but about geometrical demonstrations that give infallible assurance to all.” pg. 33

  • Errard also included a variety of practical facts in his work about recent scientific discoveries (e.g., Sieur de Linar's 1572 discovery that lengthening cannon barrels beyond 12-feet did nothing to increase projective force, heuristics about cannon use such as powder charges should be equal at least to 1/3 of the weight of the ball, and penetration rates of various cannon firing from 200 paces, minimal firing rates, recommendations on materials, and rules of thumb for batter on walls). pg. 34

  • Errard also provided a list of the requisite qualities of the engineer: “he must primarily know the force of artillery, be experienced in sieges, and be a good commander who avoids confusion in the siegeworks.” (pg. 34) Errard also recommends that, direct quote, “it is also very necessary that the Engineer also speak about all parts of the science so that he can make known that which he will have conceived for the execution of his design by geometrical demonstrations (and not mechanical ones according to the manner of the ignorant.” (pg. 34) The engineer must also be a “geometer as much for inventing machines, and other instruments serving for the defense of the fortnress and the work required, as for demonstrating the utility and profit of his inventions, as much for putting them into practice and apportioning the work to be done for the time and means available, thus avoiding excessive expense, which is usually very inconvenient, for lack of understnding of this beautiful science of geometry. Especially when he is besieged, let him think and find the means of relieving those who work, for there is nothing as insupportable as sleepiness [for both men and beasts].” He must also “know something of ordinary architecture (architecture commune) and masonry.” Errard also notes that “It is good to haunt the great” about the importance of fortification. To do this, the engineer must “study to speak briefly and intelligibly” and “that he never consent to a bad design.” Errard also makes a comment that will resonate with even modern engineers: “Let him learn rather to dispute with an ignoramus for it is to be feared, for a man who has science, to meet an ignoramus who has credit, for several reasons that everyone knows.” pg. 35

  • Langins lists the skills and roles embodied in Errard: “soldier, architect, artisan, diplomat, and skillful propagandist.” (pg. 35) Most importantly, Errard roots his approach in the rhetoric of geometry.


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