This rule is very important and is made use of in finding out the lengths and vibrations of the other notes Ri (D), Ga (E), etc., etc.

According to Rule (1) any length may be said to give the fundamental note and its Pa will be the 5th note from it. This Pa will form a perfect concord with it. This gives us the following consonant notes.

Let us take Pa (G) itself as the starting or fundamental note; then its Pa or fifth will be D in the higher octave which may be called Ri2 (D2.) Apply the formula (B)

V_n = U l/l_n; here U = 360, l= 24, and l_n = 2/3 X 24; ஃ l_n = 16.

Rule 7. Substituting the values of U, l and l_n

V_n = 360 X 24/16 = 340.

540 are the vibrations of Ri2 or Ri (D) in the 2nd octave. Therefore the vibrations of Ri in the first octave are = 1/2 X 540 = 270 Vide Rule (2).

Formula C is - l_n = U l/V_n X; substituting U = 240,l= 36 and V_n = 270,

we have  l_n = 240 X 36/270 = 32. Hence-

10. The length of Ri (D) is 32 inches and its vibrations are 270; or, the length is 8/9 1, and vibrations 9/8 U.

11. The length of Ri is 32". If we take this as the starting note then its Pa is Dha. Therefore the length of Dha is 2/3 of 32 = 21^1/3 by Rule 8 and its vibrations are 3/2 of 270 = 405.

The length of Dha (A) is 21^1/3 and its vibrations are 405. Let us take Dha as the fundamental note (Rule 1); then Ga2 (E) or Ga in 2nd octave becomes its Pa or the 5th note (Rule 9). Therefore its length is 2/3 X 21^1/3and vibrations 3/2 X 405; but these are for Ga2. Therefore according to Rule (2) the length of Ga is =2X2/3X21^1/3=2X2/3X64/3=265/3=28^4/9

and the vibrations of Ga =1/2X3/2X405=1215/4=303^3/4.

The length of Ga is 28^4/9 and its vibrations 303^3/4 (Rule 12). If we take Ga as the Fundamental note, then Ni becomes its Pa or the fifth note. Therefore

the length of Ni =2/3X28^4/9=2/3X256/9=512/27=182^6/27,

and the vibrations of Ni =3/2X303^3/4=3/2X1215/4=3645/8=455^5/8.