Hmmm....I found this online:
Are you unsure which is the lengthwise and the
crosswise grain of the fabric?
The way to tell is to let the fabric SING to you.
Place one edge of the fabric in each hand with some slack in the fabric.
Pull the fabric taught
It will make a sound.
Listen to the pitch of that sound
Now repeat in the other direction
You will notice a difference in the pitch of the sound
The HIGHER Pitch is the lengthwise grain
The LOWER Pitch is the crosswise grain.
Patsy Shields from Sulky of America
So, what do you guys think? I tried it, and I couldn't tell any difference.
You should have seen me, trying this, LOL! My son's gf walked by, and just asked what I was doing, and I said listening for the pitch, and she just shook her head and walked off, LOL!