Kiln cones
In a kiln, a set of three drooping cones can monitor the effects of temperature on the pottery items being fired.
Natural units (Part 2)
Whereas most units of measurement are arbitrary and human, Planck units are based only on four fundamental physical constants. [2 of 2]
Natural units (Part 1)
Most units of measurement are based on specific physical qualities or tangible reference objects. But they don’t have to be. [1 of 2]
Time zone tripoints
At several points around the world, three time zones meet.
Mathematical coincidence
A billionth of a century is approximately pi seconds. The diameter of the Earth is roughly half a billion inches.
Akan goldweights
From the 15th to the 19th century CE, the Akan used sets of ornate statues as a measurement system for weighing gold dust, but also encoding and reinforcing cultural knowledge at the same time.
Eclipse cycle
The saros is a measurement of time equal to 6585 days (plus one third of a day). It is the time between identical eclipses.
Electoral fairness
The Gallagher Index measures how well the makeup of a legislative body represents the proportion of votes cast to elect it. Some countries do this much better than others.
Kilometre zero
All roads lead to Rome… but where in Rome do they lead?
The Year 6000
In classical Jewish tradition, the Messianic Age – a thousand years of peace and harmony – must begin no later than 220 years from now: the Hebrew Year 6000.
The equation of time
When a day is longer or shorter than 24 hours you need to use the equation of time to bring it back into sync.
Pirates hate metric
Who keeps the metric system down? In the United States, pirates do.
One lifetime
The saeculum was a measurement of time used by the Etruscans and Romans to represent a single lifetime: no-one who witnessed the beginning of a saeculum would see its end, by definition.
Shake and barn
In nuclear physics terminology, first you need to hit the barn, and next you need to wait for 50 to 100 shakes. And then the bomb blows up.
Counting prayers
Worshippers of many different religious use beads on a string to count prayers: Catholic Christians, Muslims, Buddhists, Sikhs, Hindus, and Baháʼís.
Largest ocean current
How do you measure ocean flow? One sverdrup equals a million cubic metres of water per second. All of the world’s rivers emptying into the ocean is 1.2 sverdrups; the largest current in the world is more than a hundred times larger.