The Elfstedentocht takes place anytime the weather is cold enough that the canals connecting 11 cities in the province form a thick and relatively unbroken sheet of ice.

WSJ: Four Days Through Friesland

"It was a big thick form, maybe 30 pages, which was filled in with great difficulty because I can barely write, I can't hold a pen properly, " he said.

BBC: Entertainment & Arts

This was the discovery of graphene, a form of carbon one atom thick.

ECONOMIST: The 2010 Nobel prizes

For both modes of crystal fibre, the pattern of holes is generated by stacking hollow glass tubes a millimetre or so in diameter to form a rod several centimetres thick.

ECONOMIST: A new approach to making optical fibres

The tiny beads flatten out to form ten layers of sheets 15 microns thick, which are stacked and cooled to 100 degrees.

FORBES: Magazine Article

Once the container is spinning at the correct speed (typically a few revolutions per minute), the mercury spreads out to form a layer less than a millimetre thick, and in such a way that variations in the thickness of the mercury layer compensate for the imperfect shape of the container.

ECONOMIST: Mirror, mirror

This container is filled with 50kg of liquid argon and a thick layer of the element in its gas form.

BBC: Dark Matter: Experiment to shed light on dark particles