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Everything posted by francoisdenis

  1. That s true ! Selvin is the mathematician who made that possible. And the Vatican made him a witchcraft trial
  2. Valid??? I wonder why ....because as soon as you accept to add 5 mm to a measurement of a Strad form It becomes possible to demonstrate anything in very logical way. -do we have to add 5 mm to all the forms? - if we can add , can we remove 5 mm as well? - can I add 6 mm? etc... From this point.. that seems difficult to follow you .
  3. “and it works I was speaking of my instruments i m use to remove 7 mm to calculate the length of the form and it works well, I confirm anyway ctscan and plaster cast allow us to say that the length of a violin can vary of +\- 2 mm from the mold measurement what you do is different you add 5 mm to the mold!!!
  4. No the length with the bloc is 349 mm. That was my question: « why do you add almost 5 mm? »
  5. I agree, a 3,33 mm punto is no significant but something close to 3.5 yes I didn't know that an historical reference existed about this measure but which kind of historical link?
  6. Please answer a simple question: " what is the measurements (in mm with the blocs) of the P form ? " (then what are the measurements of the radii) and we will discussing of the interpretation later Why you never start giving the measurement in mm and how is the match with your ratio ?? without this info it is not possible to follow you forward
  7. Would you say like david: "that's a classical cremonese traditionnal outlines"?
  8. Hum..why do mean? relative measurements are more accurate that metrological mm mm are only analogical approximations of a set of relative measures . mm are what I call ''ante-engeenering ''
  9. So, that gives 1 punto=3.55 mm, using some statistic tools 25 years ago I founded the value 3.5 mm as a probable value not a bad match...
  10. I will say to the teacher "14 inches long and 8 inches wide... and voila 7:4 ratio is born." More seriously, at the time of Amati geometry is not arithmetic When you want to make something, geometry can have to deal with arithmetic the way they do that is important to understand (commodulation) inche is a metrological unit in connection with the body in a ratio between 7 and 4 the unit is one part of a term of the ratio that means something like "the relative unit of a term the ratio" you can give measurement using metrological unit and relative unit (the reason why I do a difference between metrological or relative measurement) ..that's only the beginning of the story
  11. David, what I have measured myself W=202mm L=349mm ratio W/L=0,578 root of 3 = 0,577 and 4/7= 0,571 following your measurement the length of the form should be 353,7 mm (personaly, I take measurement from my mold and it works...) Add almost 5 mm to the P form is definitely too much, you could contest the shape of the bloc but, anyway it never change the length that amount. To be clear you should: -produce your measurements, -explain how you take them and why you proceed like that -define the acceptable marge of mistake (usely +/_ 0,5mm) then -compare the result of your calculus with these original measurements, From the very beginning of this thread I defend the idea that, to be constructive, we need to agree the way we built our data of measurements to trust them and speak with others. I have some pb to understand how you work - the way you built your data remains very fuzzy for me the previous example with the P form clearly show up that problem, you add 5 mm to my measurement and say "just look" my friend . It's magic, you are a wizard. For me , the only way to go forward would be to work together on a set of the measurements I'use to do this sometime. A ctscan is a good starting point- you take the measurement and I do the same on my side then we share the result and find an agreement ratio are calculated by the software I send you a link if you are interessted in
  12. Braque and Picasso (l'homme à la guitare) ... Actually you are right for the second one (I check google image ) that true that were in close relationship at that time
  13. David, how one deals with the measurement of the overhang... that is definetly a crucial issue and your post are informative for me specially considering the paper I'm writing I have this idea in mind for many years...there is something to find ...
  14. Good , You will be happy very soon! So, Taking the form P MS 44 you used as example in the previous post you have a nice format in red with the interger 4 x7 . The picture coming from my book I'm at least sure we share the same measurements... so, W=202mm L=349mm ratio W/L=0,578 .....Why did you write 4x7 ? 202/4 x 7= 353,5 mm: definetly too much just to keep the ideal idea of integer ratio furthermore why do you not refer to the ratio W/L=0,577, the match is much more better ? is it because it comes from an irrational construction with the square? Do you contest the use of squares by crafmen... ? David, you like to post historical pictures to support your generous post, I'm posting some. (notice the integer approximation of the irrational value of roots of 2 by the relation 5-7 (figure up to the left) Could you tell me in which chapter where Vitruvius mention phi? And Da Vinci used the square as a base of architectural projects (and for Joaquim, he knowed also the principe of the volute (drawn free hand) it is not the golden section (note how is corrected his first try still visible)
  15. There are parts (unit fraction) which can varie , Ok, and? I'm not sure to understand what you want demonstrate here in connection with my question.. Bt may be I understood why you state to never deal with irrational number . Actually you said that you take account of the overhang or not. Doing that, you change the data in a way which allows to shift from an irrational ratio to a rational one if I take my previous example for the measurement of the C bout in relation to an upper part =208 mm I showed that the difference between the approximation (by integers 5-7) and root of 2 was only 0,5 mm so the the C bout will be = 86,6 mm if you remove the overhang the measurement becomes 204,5 and the ratio shift to 3-4 (rather than 5-7) . In a musical scale , this is an alteration of a semi-tonus. I gave in my paper of the Strad mag of august about the pythagorian tonus some examples of variations based on the tonus and semi-tonus . You are right, including or excluding the overhang you will probably erase some irrational relations. But including or excluding the overhang only for that purpose....why? could you explain? And....I really wonder why you you are so in love with the VP (nothing more that the first ratio sesquialtere - 3 circles in a quadrilatère 3 by 2 ) VP is just a possibility among others, when I take accurate measurements, real VP are rare, more often the radii doesn't divide the LB in 3 equal parts. I regret that because VP is so simple...
  16. David, you seem to reject irrational relation that you never come across. I'm estonish for two reasons. -irrationnal relations come easely using a compass -for some good reason, irrationnal used by the ancient come mainly of the polygone having only 1 diagonnal (another symbole of the VP :) Close rationnal mesasurement of these irrationnal relations were used. For example, you know that the harmonique section is commun, If you set the upper corner with this section the hight of the C bout will be 208 mm x 0,414=86,1 mm with the approximation 5-7 208 mm x5/12= 86,6 mm So I have to understand that, working like you do, you can appreciate a deviation O,5 mm I can't follow you on this point.
  17. Concepts and theories have been used and that is really fascinating to study them. Founded on deep ancestral empirical pratices it is amazing how smart they are. Unfortunately, that's also not easy to grasp for us.... a lot of confusion about this. The only "technical drawing" we have, the drawing of a luth of the XV°S, give us some interesting keys. From "concept and theory" emerge "the recipe" and from the recipe emerge "the making". Ratios appears in the recipe but often change during the making process. The recipe worked like a memo which support the making and the theory made the recipe. It's an optimazed and rational system in the context of that time. Our system is also an optimazed and rational system in the context of our time. I will not say that. The VP is a representation of the trinity, a symbol in many Ancient cultures for fecondity, creativity, arithmetic, geometry, music, divinity etc.. VS contains the principe of the section (1+(1+1)) and the symmetry (1+(1)+1) It is the section of the arithmetic proportion. It's always surprizing for me to notice that its fascinating power is still alive VP was use as much as possible as a symbole but we have not to stick to the letter