francoisdenis

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About francoisdenis

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  1. Violin geometry references

    Hi Ben I ended the drawing in a more explicit way. As often, differences are easier to characterize than similitude. To show up this I added the example of a viola framework which respectc almost the same order than your viol to get the measurements, only the ratios are changing. It's an illustration of what I try to explain: "proportions" of a text are only a superficial indication of the deeper order which manage the forms. Furthermore It's also true for images. A lot to say...
  2. Violin geometry references

    So, it's very fresh OK I did with your picture 1) I draw the outline _ 2 I check the symmetry 3- I draw the average 4 I set the line 5 Letters to be clear So Measurements are in pixels PQ= 1095 XQ=656 PX=439 ZQ=387 XZ=279 pp'=656 aa'=435 bb'=249 ee'=407 qq'=545 The framework is clear enought The surface pp'/PQ=0,599 close to 0,6 ratio 3-5 In the lenght pp'/XQ=1/1 (a square) PX/XQ = 0,669 close to 0,666 ratio 2-3 XZ/ZQ= 0,720 close to 0,714 ratio 5-7 In the width aa'/pp'= 0,663 close to 0,666 ratio 2-3 bb'/aa' = 0,572 close 0,571 ratio 4-7 qq'/bb'= 0,83 ratio 5-6 ee' /qq' = 0,746 close to 0,75 ratio 3-4 I just follow here the teaching of the Zwolle luth! but they are many other theaching than we can get from this....may be tomorow I have to go to work a bit
  3. Violin geometry references

    One can also wonder what was the knowledge of the maestro himself ! (speaking of proportion, measurements, etc...). Actually, if one sticks to a margin of error of +/- 0.75 mm, no shape of the master is entirely traced with the ruler and the compass. But that proves nothing, forms could have been disappeared. Up to a contrary proof, these forms are empirical adaptations made from pre-existing pattern themself made according to the Amati family standart. Subject to a more thorough study the PM 1062 form (without attribution) could be one of these original patterns. it's pretty tempting to believe. The alteration of the original models of the Amati family is certainly a cause of decadence. Moreover this phenomenon is not unique to the violin making. Since ancient times, some complain about workers who have the bad habit of reproducing jigs more and more badly damn... There is nothing new under the sun
  4. Violin geometry references

    Hi ben, do you have the measurement in mm of the viol because the rather bad perspective of the picture change the analysis. (I had several viols in my repertory and would be happy to work on this one too, if you mind) I need Lenght from bottom to the top but without the saddle of the neck ( measurement on the table) lenght of bottom and middle part maximun width lower bout, C holes, upper bout minimum width middle bout and Choles
  5. Violin geometry references

    Regardless! As I said, I found an interest to understand! Ok, we are all different, limits and orientations of our curiosity vary. Some people may be satisfied using the 1/7 ratio to set the bassbar and other people will be interested to know that this unit fraction is related to a fifth and fourth division. We can be satisfied to know that the ratio 7- 4 is one of the most common but we can be curious about other types of surfaces (often close).
  6. Violin geometry references

    What I'm trying to explain is that Zwolle's lute interesst is not in the choice of the ratio nor in its form but in the indications which it gives on a specific pratice that macons of that time call "the extraction of the measurement". This expression simply means that , A,B,C,D being dimensions we go from A to B then B to C, C to D, etc. Each dimension is dependent of a previous one. It is this order that is so important to know. Zwolle's luth is only that, the teaching of "the extration od the measurement" . So, when he recommands to give the length of the neck equal to the width of the body, the value of the ratio (1-1) is not important. The important point is "A to B " the lengh of the neck has to be relative to the width of the body. One do not forget that we are in oral tradition context where craft never received knowledge through the writing. From this point of view the sequence of the instructions is important, no notes book, remember, cathedrals, ships, musical instruments, furnitures were buit and no notes book. Oral tradition understanding is quite challenging...
  7. Violin geometry references

    Hi Ben The lute of Zwolle is part of a corpus of elements of various origins and Zwolle was not manufacturing lutes (or harpsichords for that matter) but was astrologer. This lute is problematic because its image does not correspond to anything known in XV ° S but it is precisely there that we find the most interesting element. The drawing is probably inspired by earlier Arab sources of at least two centuries (on this subject, see C.Rault n: String Instruments from the Middle Ages, Créaphis, Rencontres Collection at Royaumont, Grâne, 1999. pp. 49-75.) . In the Eastern culture, the "ud" (lute) plays the same role as the monochord in the West. It is the instrument of the scholars used for theoretical teachings of music of course but also arithmetic and other parts of the quadrivium. As I wrote in my previous post, believing that this drawing is a plan is the projection of a modern idea. It is actually an "exempla" that is to say an oral teaching medium. There was an error of interpretation. This drawing hidde a grammar that allows us to read all kinds of forms, it is polysemous and it's not nothing (hi Dan Brown I get the rights). Moreover, this discrepancy between the observable reality and the writing is the norm before the invention of the printing press. One do not waste parchment to describe one thing but one tends towards the universal. With the printing everything changes, the knowledge becomes exportable, there is a rupture of the obligated link which bound the taught to the teacher. Very quickly we try to transmit selfexplicative knowledge other than the Bible, architectural treatises follow one another and these texts say a lot about the evolution of society during the Renaissance. The look changes and the progress in a century between the publications of a matthias Rorictzer at the end of the XV ° C, a Vincenzo Scamozzi in the middle of the XVI ° S and a Guarino Guarini (beginning of XVII ° S) is hudge. With Rorictzer it is still antiquity, with Guarini it is already the nineteenth century, it is us. It is clear that something essential has happened, a page is turned. Of course, in detail, everything is not so linear there are back and forth, brakes and acceleration but the violin is definitely an instrument of the other world. It is in continuity with what the Zwolle manuscript teaches us. There is no doubt about it. A few years ago a guitar maker came to see me to redesign a Selmert guitar to his taste, he came and was satisfied and furthermore it has been an easy job . Do we have to speak of "pro-engeneering" in this case
  8. Violin geometry references

    To pursuie my previous post Ratio, proportion or unit fraction are used indistinctly to mean specific relations internal to the violin. In this sense, they are distinguished from our casual measures which are ratios to an external reference (meter). We all know the ratio 4/5 which often links the lower bout to the upper bout or the fraction 1/7 proposed by Sacconi to set the bass bar. But we do not know anything about the origin of this ratio and fraction. When other values appear like 13/16 rather than 4/5 (Nicolo Amati and Strad) or fractions 1/4 and 1/5 to set the viols bass bars, one remains without convincing explanations. David Burguess can post on MN "may be" or "why" and he is right because there exist according to the violins that one measures, dozens this occasional relations of which one can quite reasonably think like David does that, "if one search them one finds them ". In Fine, finding "proportions" in a violin seems to mean nothing but apparently casual internal relationships. Nothing very interesting here for me. This wise observation has long kept me away from the subject (until a severe and persistent insomnia decides otherwise). The ancient texts are filled with these "occasional" proportions without accessible meaning. Thus, the proportions of the ancient temples do not correspond or that very partially to the recommendations of Vitruvius, the Lute of Arnault de Zwolle seems to have existed only in his imagination etc.. .. In the 1970s Richard Tobin publishes "the Canon Polykleitos" and then come from other publications in the 1990s Louis Frey publishes "Architectural Data and Hypothesis on Pre-Euclidean Mathematics" and Pierre Gros "" Irrational Number and Perfect Number at Vitruvius " ), recognized commentator of Vitruvius with whom I come into epistolary contact (no email at this time) and who adroitly advises me.These publications defend the idea that the proportional sections and their approximations provide a plausible explanation to the origin "ratio". Take our previous example, the fraction 1/7, this measurement is taken from the center of the instrument which is to say that the width is divided into 14 and that the bass bar is positioned by 6 parts on one side and 8 parts of the other. This division corresponds to a section 3-4 (6-8), a fourth. It's starting to get more interesting... The fourth is one of the possible approximations of a proportional section called "harmonic". The two approximations that "frame" 3-4 are 2-3 and 5-7. The measure becomes predictable 2-3 and 5-7 are two possible alternatives of 3-4 and "cerise sur le gâteau" (icing on the cake), the average of the difference between 2-3 and 3-4 gives you the avrage thickness of the bass bar which otherwise corresponds to what is called the "Pythagorean tone". So, we went from a simple measurement injunction to a reasoned knowledge. That's a lot more exciting, (at least for me). After a few sleepless nights I published a book in 2006 "Treaty of violin making, the violin and the art of measurement" in which I continued and I hope thorough, the works of my predecessors. The book is based on the analysis of a technical plan of a string instrument, a lute. The document (middle XV ° C) is known but I revisit its interpretation. Zwolle gives some simple relations like tthe settings of the bridge and sound hole. But it appears that these few indications of "relative measures" (ratio) are however contradictory. The important thing is that I demonstrate that these contradictions can be explained by the use of approximations of the proportional sections. (I don't receive to date any critic about the validity of my demonstration but I have to admit that, unfortunately, these 30 pages are rather tricky to grasp for many) In conclusion, the lute of Zwolle is not a drawing in the sense we understand it but an "exempla", that is to say, a teaching medium on the way to take measurements. Wow! doors open, what happens if I apply this teaching to the form of the violin ? It happens that many things are rationally explained that the connection between a 4/5 and 13/16 becomes clear, it happens that sense arrives in the system. Sorry to have been a bit long but it was a complement to my previous post on the interest of talking about "relative measure" instead of "proportion".
  9. Sorry Ben, I forget that it was a private message. Actually I solicited here the legendary british sense of humor  :)

  10. Violin geometry references

    40/5000 It will happen to Michelangelo later
  11. Violin geometry references

    Excellent!, any reference?
  12. Violin geometry references

    "I'm using geometry, construction, ratio, and proportion in ways that I believe are clear enough to be understood. For me, that's enough." Deard David I can follow you when you talk about the use of relative measurements for yourself. As you say, the words ratio, proportion and unitary fraction, are interchangeable for you and readers. The important thing here is to signify a relationship specific to the object. Note that you exclude locally the common unit of measures (mm) for the specific unit of the relation "comparing things by simple integer counts of a shared unit". I am not so convinced that this last point, I mean the exclusion of the concept of unity from the set of numbers (Euclid) is perfectly clear to ordinary readers. But things are different if we speak from a historical point of view. So, ratio, proportions, measures, unity, symmetry, part, analogy, module, justification .... These words can not be understood according to our common sense. As a result, the interpretation of texts is difficult and often remains obscure despite the efforts of generations of translators. Here "the casual use" is insufficient. So the importance of the accuracy of terms depends on whether you are in exegesis or not. I spent nights and nights, thousands of hours trying to understand what practices were hidden behind these words. How thoughts have been organized to produce these objects I think I am well placed to say that it is precisely in the hidden and forgotten senses that the keys of the thought of the ancients are found. I suggest the term "relative measures" because it is correct in both contexts. That's all. For the rest I understand that you use a ratio / relative measures framework for the construction like vaults is that? Any drawings to share ?
  13. Violin geometry references

    nothing to save just close your eyes and pray
  14. Violin geometry references

    Personnaly I have a soft spot for Cesariano. His work shows in a very interessting way, the transition to the Renaissance Ben do you appreciate the subtle inclination of the penis ?
  15. Violin geometry references