It turns out that there is a mathematical proof that up to six people occupy the smallest possible sleeping bag volume if they lie down beside each other but that seven people will take up their smallest possible sleeping compartment if they lie in a ’rounder’, 2-on-top-of-3-on-top-of-2 arrangement (however improbable/uncomfortable that seems).
Today’s invention is a slightly more practical application of this idea to the problem of laying pipework underground.
If there are 6 or fewer parallel, circular-section pipes, the required volume of earth to be removed will be minimised if these are laid side by side. If you need to bury more than 6 such conduits, they will require the least possible digging if placed in a ‘hexagonal’ arrangement.
For long pipelines, this difference could represent a substantial saving in time and energy.