On 24/02/17 09:01, Nick Maclaren wrote:

If tripods did not have a serious disadvantage over tetrapods, they
would have replaced the latter millennia ago, because they are simpler
to make, lighter and (as you say) easier to position.

Not entirely - they are less suitable for building work. With a tree or
a hedge, you can get the 3rd leg around the tree or through the hedge.

With a building, you can't and that puts the top, which is not as wide
as the 2 step bearing legs, well away from where you want to be.

I don't think it is a simple as "one is better". They are made for
different purposes and each suits its purpose better than the other,
mostly (there are always exceptions).

Cheers, Tim