A thread that was posted earlier this fall got me to thinking..... 

how do you actually determine the test weight of ear corn. 

And my high school chemistry/ physics training came to mind.......

you can determine the volume of an item by determining the amount of water it displaces. 

So, weigh an ear of corn - or 10 ears if you prefer.

Then, fill a container level full of water, a container that you can determine how much water it holds. 

Place the ear - or 10 ears of corn in the water.  Let the excess water run out.

Then remove the ears from the water (that's the tricky part.)

Then determine how much water was displaced. 

Finally, since you have the weight of the corn, and the volume, you should be able to calculate out the weight/volume, or test weight.

Viola!  There you have it!

Edit:  at some point in the process, I would want to measure the kernal moisture of that corn, and document it, since test weight will vary with moisture levels.  THAT becomes another one of those "tricky parts".