Circular section line - Circular section line

...These sounds determine the tone of a bell, and especially the important lingering sound, are the sounds of the bell's natural vibration. Because real bells come in a variety of sizes and shapes, the frequency and state of their natural vibrations are not all the same, but the nodal lines (lines on which no vibration occurs) that appear in the natural vibrations include meridian nodal lines that run vertically so as to divide the side of the bell equally, and circular nodal lines that go around the bell horizontally, and the natural vibrations can be classified by their combination. The fundamental vibration that produces the fundamental tone has only four meridian nodal lines as shown in Figure 2, and the partial tone with the next lowest frequency after the fundamental tone (called the first overtone) has only six meridian nodal lines. ...

*Some of the terminology explanations that refer to "circular nodal line" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…鐘の音色を決めるこれらの音，特に重要な余韻となる音は鐘の固有振動の音である。　実在の鐘は大きさや形がいろいろであるから，その固有振動の振動数や振動の状態も同じにはならないが，固有振動に現れる節線(振動が生じない線)には鐘の側面を等分するように縦に生じる子午線節線と，鐘を横にぐるりと回る円形節線とがあり，その組合せによって固有振動を分類することができる。基本音を生じる基本振動は図2に示すような4本の子午線節線のみをもち，基本音の次に振動数が少ない部分音(第1上音という)は6本の子午線節線のみをもつ。…

※「円形節線」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報