மகா---ஸ்ரீ தேவால் (Mr. Deval) தெற்கு மகாராஷ்டிர தேசத்தைச் சேர்ந்த சங்கிலி என்னுமூரிலுள்ளவர். இவர் இந்திய சங்கீதத்தில் ஒரு ஸ்தாயியில் 22 சுருதிகள் இருக்கிறதென்று ஒரு நூல் எழுதியிருக்கிறார். அதில் 22 சுருதிகள் செய்யும் விதத்தைப் பற்றி எழுதிய விதிகள் பதின்மூன்றும் பின்வருமாறு :-

1. "The whole length of the wire between the two fixed bridges gives the Fundamental Note Sa 1 (C1 ). Let the length of the wire be 36 inches, the note produced be called Sa 1 (C1 ) and let its vibrations be 240 per second.

2. The note produced on half the length is in value equal to Sa 1 (C1 ) and in pitch or vibrations it is double the Fundamental Note.

The note produced on the length 18" is therefore Sa 1 (C1 ) itself, but one octave higher. Let this note be called Sa2 (O2 ) to distinguish it from Sa 1 (C1 ) the F. N. ; then the vibrations of Sa2 (C2 ) are double i. e. 2 240 = 480 per second.

3. The pitch of a note or its vibrations are inversely proportional to the length of the wire.

This rule is a legitimate inference from the above two rules. Rule (1) permits us to take any length for the Fundamental Note (F.N.) and according to rule (2) if the length is halved the pitch is doubled, and if the length is doubled the pitch or the number of vibrations is halved. If therefore length is taken the pitch or the number of vibrations produced will be rebled. Or by generalization :

4. The pitch varies inversely as the length and vice versa.

The above four rules may therefore be put in the form of a simple Formula for convenience of working and ready reference.

Let V_n = vibrations or pitch of the note on wire L_n inches long. U_n = The vibrations or pitch of Sa 1 (C1 ) the F. N. here = 240.

L = the length of the wire of the F. N. here = 36 inches = 36"

Then:

V_n X l_n= U X l ...................................(A)

V_n = U X l / l_n ................................(B)

l_n = U X l / V_n .................................(C)

                     therefore if V_n = 2 U

        l_n = l / 2..................................(D)