I'm inclined to think the illustration was made to show tenons projecting through to the top surface merely to convey the fact there WERE tenons, which couldn't be clearly shown otherwise.
Anyone familiar with woodworking - and more people were in those days maybe - would know that having tenons as long as that would be totally impracticable, strengthwise and assemblywise.
IMO the actual tenons are actually pretty sophisticated since their "bulbous cone" shape allows for considerable subsequent structural movement without structural failure. I reckon they were very clever people with a long term view.
 Reply | with quote | Posted by nigelswift
20th December 2006ce
11:19 |
|
Head To Head 
Stonehenge lintel holes (Pete G)