On Wed, 20 Jul 2005 10:36:29 GMT, "PC Paul" wrote:

I saw a picture a while back on rec.woodworking of a Japanese temple pillar
done with a totally impossible dovetail butt joint cut in 16"+ timbers...

Probably a shiho kama tsugi - the four-faced gooseneck joint. This has a
gooseneck tenon, but it appears to have one on each of the four sides.
Like most of these "impossible" joints to assemble, it's a diagonal
slide to assemble it.

It's not a particularly good joint, because it offers no location along
the 45° plane (that's how you assemble it). It's impressive though, so
it's largely a decorative feature.