TheScullster wrote:

"The Natural Philosopher" wrote

The Medway Handyman wrote:
Three poles in a triangle, one longer that the other two, used with a
block & tackle attached to the longer one?

Its on the tip of my tongue!

sheerlegs?

Apparently spelt shear legs.
Not quite sure why, when the legs are in compression!
See http://www.hss.com/g/69310/500kg-Shearlegs.html for details.

The word originally comes from "sheer" = steep.

"Shearlegs" is simply a spelling error. Since it's a common one, the
dictionaries feel obliged to record it (as they also record "sheering"
sheep) but being in a dictionary don't make it right.



--
Ian White