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Figure 1: Transition of cross-section line drawing of bastion and curtain into more detailed profileWe are well informed about the teaching materials of the Van Schooten family. Leiden University holds several manuscripts. First, there is the autograph of Frans van Schooten Sr. mentioning explicitly his name in the part on fortification with the title Mathematische Wercken door F. van Schooten in multiple parts dealing with geometry, surveying and fortification. Another anonymous manuscript (here called the Lombaerde manuscript after the private owner who reconstructed the order of it). It has a very similar layout of pages, although the handwriting of the Leiden manuscript is in cursive unlike the Leiden copy and therefore it is hard to establish whether the two indeed could be written by the same hand. The Leiden manuscript has been colored in beautifully with much attention to presentation not only in its appearance but also in its contents. It contains for instance many examples how to translate step by step two-dimensional line drawings into three dimensional ones and details such as complete scale rods. Sources: Frans van Schooten Sr. BPL 1013 [fol. 219 v. and fol. 220 v.] (right)
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BPL 1013 Full color illustrations are available at Leiden University Libraries Digital Collections.Persistent URL to Leiden University Libraries Digital Collections The rights status of this resource is public domain | |||||||||||||||||||||||||||||||||||||||||||
Figure 2: Two bastions and curtain with definitionsFollowing the academic custom of the time, Frans van Schooten Sr. opens his manuscript with definitions and propositions. Sources: Lombaerde manuscript [fol. 1 r.] (left): and Frans van Schooten Sr. BPL 1013 [fol. 134 r.] (right).
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BPL 10133 Full color illustrations are available at Leiden University Libraries Digital Collections.Persistent URL to Leiden University Libraries Digital Collections The rights status of this resource is public domain | |||||||||||||||||||||||||||||||||||||||||||
Figure X: Design pentagonal fortress with corner and curtain bastionsSimon Stevin favored the regular hexagonal citadel, but his successors showed concepts with pentagonal or hexagonal plans as ideal, although in practice terrain conditions called for other, less regular layouts. In HS 441, Pieter van Schooten described a pentagonal Small Royal with a bastion angle which is 30° more than one-thirds of the polygon angle. He describes a typical Small Royal fortification with a 60 rod distance between the points of the two bastions. a mathematical analysis of Petrus van Schooten pentagonal fortress
Sources: Petrus van Schooten Groningen University Library, HS 441 [fol 173.] and Christiaan Huygens, Leiden University Library, Hug 16 [fol. 31 r.].
On request of the publisher, this drawing was removed from the article. Four illustrations was the maximum allowed. |
HS 441 Full color illustrations are available at University of Groningen Library, Special Collections.Persistent URL to University of Groningen Library, Special Collections Copyright UBG. Free use for non-commercial purposes. In publications, "University of Groningen Library, Special Collections" must be mentioned as source. | |||||||||||||||||||||||||||||||||||||||||||
Figure 3: Design two bastions and curtain with complex goniometric rulesSurprisingly enough the layout of the more complex irregular fortifications followed basic rules while the explanation of the most elementary parts of fortification, the design of two bastions with the intermediate curtain or the construction of regular fortresses, sometimes included alternative, more complex mathematical rules. They included cosines, tangent, and secant rules and trigonometrical tables. A less surprising observation is that mathematicians rather than engineers with merely fortification expertise were using these more complex explanations or trigonometrical tables to demonstrate that the time-consuming step-by-step geometrical constructions could be replaced by alternative goniometric rules. a mathematical analysis of Petrus van Schooten
Sources are Lombaerde manuscript [fol. 10 v.] and Petrus van Schooten BPL 1993 [fol. 9 r.].
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BPL 1993 Full color illustrations are available at Leiden University Libraries Digital Collections. Persistent URL to Leiden University Libraries Digital Collections
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Figure 4: GeoGebra overlay of two fortification systemsHenk Hietbrink set up a rich website to encourage pupils to build their own fortresses, to analyse in the e-book Fortification in the sixteenth and seventeenth century,
included in the digital educational system GeoGebra, the geometrical constructions and calculations of fortifications in handwritten and printed treatises on military architecture
and to compare these historical examples by overlaying their designs.
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GeoGebra You can draw a fortress of your own to investigate the relationships between sides and angles. You can use this animation to compare fortifications schemes of eminent engineers. You can use this animation to compare more than 200 drawings of fortifications. GeoGebra Book: Fortification in the Netherlands in the 17th century | |||||||||||||||||||||||||||||||||||||||||||
Table 1: Comparative analysis manuscripts/publications on fortificationTo test our hypotheses the following questions were formulated: Can we detect some order in the design methods for the layout of fortifications and do these changes over time in correspondence with former statements of various styles in fortification? Can we detect some order in the mathematical construction and calculations of the geometrical figures underlying the design of fortifications proposed in the manuscripts and printed works, and changes herein? How complex are these design methods, are they more complex than required for the layout of fortification, and does the complexity increase over time? Although far more research needs to be done, we came to the following observations based on this preliminary comparative analysis. Detailed description of all the fortifications mentioned in the table. | ||||||||||||||||||||||||||||||||||||||||||||
Manuscripts/Primary SourcesThis list links to a webpage with more details and references to online libraries
Literature
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