Am I wrong, or is my book wrong?

[Evil Undead]

Probably (almost definitely) me, but I want to make sure.

I'm reading Bass Guitar For Dummies, and it's great but I'm not sure about the diagram below.

It says that a Major 3rd will always look like this. But for example, what if you want to use the C major scale and want to find a 3rd up from D - would that not mean an extra fret between? Or is that getting in to a whole new can of modes etc?

http://pbckt.com/pU.uc9WAp

[Schlyder]

Yes an interval of a major 3rd will look like that.
And yes you are getting involved into modes (and the Harmonized Major Scale) if you want to stay in C Major and go up a third from D.
You would have a minor 3rd, if you are going up a diatonic 3rd from D ( D to F), in the key of C Major.

[fearceol]

More about intervals here :

Bass Lessons : Intervals

[MonkeyBass]

If the root note changes (ie your root was a C now it's a D) then that will always be a Maj 3rd. So if the root is C the Maj 3rd is E, if the root is D the Maj 3rd is F#. If the root is E the Maj 3rd is G#, etc...

[Nev375]

Unless you are using some strange non-standard tuning, then yes all of your intervals will stay in their same relative positions across the fretboard.

Your third will always be one string higher and one fret lower.
Your fifth will be one string and 2 frets higher or one string lower on the same fret. etc...

[MalcolmAmos]

Major Scale Box. 

G|-------|---2---|-------|---3---|---4---| 1st string
D|-------|---6---|-------|---7---|---8---|
A|--b3---|---3---|---4---|-------|---5---|
E|-------|-------|---R---|-------|---2---|--b3---|4th string

Not sure this was talked about --- you can grab that minor 3rd (b3) as shown in Dummies or on the E string one fret up the neck from the 2. Both will be b3's.

I like using the b3 on the E string - no reason beyond personal choice. Use whichever one you like.

Happy holidays.

[GeoffT]

Originally Posted by Evil Undead

It says that a Major 3rd will always look like this.

That relationship of going up a string (in pitch) and back a fret (toward the nut) will always be a Major 3rd (provided you are using standard tuning in 4ths) but it is not the ONLY option for playing a root and it's Major 3rd, so the statement is a bit misleading.

For example (all references to up or down on strings relate to pitch):
-Same string up 4 frets is a Major 3rd
-Down a string and back 3 frets is a Major 3rd (an octave lower)
-Down 2 stings and up 2 frets is a Major 3rd (an octave lower)
-Up 3 strings and up 1 fret is a Major 3rd (an octave higher, also sometimes referred to as a Major 10th but still a Major 3rd with respect to the root)

If you accept that statement as true and that is the only way to play a Major 3rd, then that is the only option you will ever have for playing the Major 3rd. At some point you will want to use the other options, so IMO it is best to learn them now so that they are all available, rather than having to "unlearn" that one way as your only option.