There's a basic explanation here:
http://billfitzmaurice.com/phpBB2/viewtopic.php?t=1293
Hmm so an 8x10 cab should be built so that each line of four are at 90 degrees to each other?
I don't think that a line of 8 10 inch speakers on top of each other is going to be the most practical. Unless your planning on bolting it to the floor