At the 2006 Time Ceremony, we saw the extraordinary sight of Fellows Quad almost empty of people, except for a huge traffic jam on the North side, with no apparent cause.
This was an example of a phenomenon known to engineers as a shock wave.
Very often, the individuals in a crowd adjust their speed taking into account only their immediate neighbours. On a motorway, many drivers fail to look any further ahead than the one or two cars in front of them. In normal circumstances, this is perfectly safe: on approaching an obstruction, the nearest cars slow down, causing others to slow down behind them, and so on. Eventually, cars which are so far away that they cannot possibly see the obstruction itself nevertheless slow down, purely relying on the speed and spacing of the cars immediately in front of them.
However, if the obstruction is too severe, or if the general speed is too fast, the spacing becomes less and less, until, perhaps a mile "upstream", the spacing becomes negative ­ which of course means that there is a collision.
Similarly, "knocking" in a central heating system is not caused by air bubbles (whatever the installers may say), but by a shock wave (usually resulting from having installed a valve which is too small and therefore causes too great an obstruction).
Other well-known shock waves are those behind a supersonic airplane, and the magnetopause and heliopause.
This is exactly what we saw in Fellows' Quad - the general speed was getting gradually faster during the hour, and eventually was sufficiently fast that, when someone caused a delay which would not have mattered at a slightly slower speed (perhaps pausing to pick up a dropped mortar-board?), probably on the West side of the Quad, everyone "upstream" adjusted their speed and spacing in such a way that the spacing became negative on the North side of the Quad.
Result - gridlock, for no apparent reason!

The Oxford English Dictionary gives the origin of "swift" (the bird) as the root "swaef...", meaning "sweep", and referring to the sweeping nature of a swift's flight.
While true, this is grossly misleading.
Most "sw..." words denote circular concepts: for example, the archaic word "swive" means "to screw" (in both senses).
We are used to sweeping with a broom with a head perpendicular to the handle, and with bristles perpendicular to the head: it has to be used with linear strokes.
But in the old days, a broom had no head: the bristles were directly connected to the handle, and it was normally used with small circular movements.
The common swift is a remarkable bird in that it spends virtually its entire life in the air (http://www.oum.ox.ac.uk/learning/htmls/swifts.htm): it even sleeps "on the wing". It remains aloft primarily using thermals, therefore characteristically making "lazy circles in the sky".
So the OED is right to refer to the sweeping nature of a swift's flight, provided that this is understood to mean its circular flight.

The Time Ceremony is not a race. You do not collect £200 each time you pass the Tower of Four Orders. It is a journey in time, and you do not reach the end any sooner by going faster in space.
The Time Ceremony should be a gentle stroll. Take time to talk (in whispers, of course) to the people around you.
There is skill, not in overtaking, but in undertaking, the technique of changing places with the people in front by walking slightly slower than them.
Do not walk as if your ankles are tied together: you will go much slower if you take longer steps, putting the toes down first, rocking back onto the heel, then leisurely dragging the front foot backwards to begin the next step.
If you must twirl at the corners, do not link arms with five others and propel the sidesmen at almost superhuman speeds. Link arms with at most one other peron, drift out of the mainstream, and twirl gently.
Even "whirling Dervishes" do not twirl fast.
You may even like to adopt the practice, loved by some old-timers, of "trailling" at the corners, consisting of wrapping your gown around yourself and twirling extremely slowly, with your head down and your chin tucked in and muttering into an imaginary beard.
Do not be quadhogs.
Be ground-swifts: make lazy circles on the ground!