1638 __ « Discorsi e Dimostrazioni Matematiche, intorno a due nuove scienze »
‣ Comment : Galileo was the first to relate pitch to frequency of vibration. This discovery was first published in 1638, in dialogue form. — “The Discourses and Mathematical Demonstrations Relating to Two New Sciences” (“Discorsi e dimostrazioni matematiche, intorno a due nuove scienze”, 1638) was Galileo's final book and a sort of scientific testament covering much of his work in physics over the preceding thirty years. (Compiled from various sources)
‣ Original excerpt : « Salviati. — [...] Impelled by your queries I may give you some of my ideas concerning certain problems in music, a splendid subject, upon which so many eminent men have written : among these is Aristotle himself who has discussed numerous interesting acoustical questions. Accordingly, if on the basis of some easy and tangible experiments, I shall explain some striking phenomena in the domain of sound, I trust my explanations will meet your approval. [...] — Your illustration makes my meaning clear and is quite as well fitted, as what I have just said, to explain the wonderful phenomenon of the strings of the cittern or of the spinet, namely, the fact that a vibrating string will set another string in motion and cause it to sound not only when the latter is in unison but even it differs from the former by body, which spread through the air, bringing to the tympanum of the ear a stimulus which the mind translates into sound, But since these waves in the water last only so long as the friction of the finger continues and are, even then, not constant but are always forming and disappearing, would is not be a fine thing if one had the ability to produce waves which would persist for a long while, even months and years, so as to easily measure and count them ? [...] — The device is one which I hit upon by accident; my part consists merely in the observation of it and in the appreciation of its value as a confirmation of something to which I had given profound consideration, and yet the device is, in itself, rather common. As I was scraping a brass plate with a sharp iron chisel in order to remove some spots from it and was running the chisel rather rapidly over it, I once or twice, during many strokes, heard the plate emit a rather strong and clear whistling sound: on looking at the plate more carefully, I noticed a long row of fine streaks parallel and equidistant from one another. Scraping with the chisel over and over again, I noticed that it was only when the plate emitted this hissing noise that any marks were left upon it; when the scraping was not accompanied by this sibilant note there was not the least trace of such marks. Repeating the trick several times and making the stroke, now with greater now with less speed, the whistling followed with a pitch which was correspondingly higher and lower. I noted also that the marks made when the tones were higher were closer together; but when the tones were deeper, they were farther apart. I also observed that when, during a single stroke, the speed increased toward the end the sound became sharper and the streaks grew closer together, but always in such a way as to remain sharply defined and equidistant. Besides whenever the stroke was accompanied by hissing I felt the chisel tremble in my grasp and a sort of shiver run through my hand. In short we see and hear in the case of the chisel precisely that which is seen and heard in the case of a whisper followed by a loud voice; for, when the breath is emitted without the production of a tone, one does not feel either in the throat or mouth any motion to speak of in comparison with that which is felt in the larynx and upper part of the throat when the voice is used, especially when the tones employed are low and strong. [...] » (Translated from the Italian and Latin into English by Henry Crew and Alfonso de Salvio.)
‣ Source : Galileo Galilei (1638), “Dialogues Concerning Two New Sciences”, translated by Henry Crew and Alfonso de Salvio, New York : Macmillan & New York: Dover Publications, 1914, pp. 95-104.
‣ Source : Wayne, Dennis (2007), "Readings in the History of Psychology", Edited by Richard M. Elliott, The Century Psychology Series, Read Book, pp. 17-24.
‣ Urls : http://www.law.umkc.edu/faculty/projects/FTrials/galileo/dialogue.html (last visited ) http://oll.libertyfund.org/?option=com_staticxt&staticfile=show.php%3Ftitle=753&chapter=109891&layout=html&Itemid=27 (last visited ) http://www.liberliber.it/biblioteca/g/galilei/discorsi_e_dimostrazioni_matematiche_intorno_a_due_nuove_etc/pdf/discor_p.pdf (last visited ) http://galileoandeinstein.physics.virginia.edu/tns_draft/index.html (last visited )
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