Primary designs

[ANTarchimedes-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

    What different things are supposed to be achieved by the different 
primary designs?  By knowing this, I might be able to experiment better with 
different primary designs.  Also, which primary shape did Tesla most 
frequesntly use?

Nick Moor