Arthur C Clarke once proposed anisotropic travelators composed of fluid flowing faster in the middle than on the edge, but resistant to vertical penetration. It seems to me that such an anisotropic fluid exists, but with a proviso: it doesn't flow under impact. Therefore, this can be done, as follows.

Take a trench sloping longitudinally downhill. Pump custard in at the top and allow it to flow downhill. It will, like other fluids, flow more rapidly in the middle than at the edges. When it reaches the bottom, pump it back up again through a pipeline. Then the cycle repeats. This can act as a travelator, provided the pedestrians sprint down its length. They keep fit and get there faster, and to an extent get to choose their speed. They can also step on and off easily by moving on and off at the edges.

Of course, if they stop moving for any reason, they sink into the custard, which serves them right for being lazy.
-- nineteenthly, Mar 30 2008

Where does supply of custard at the top come from?
-- Dub, Mar 30 2008


Birds, of course.
-- AbsintheWithoutLeave, Mar 30 2008


I bet thix will only work in a tropic environment.
-- 2 fries shy of a happy meal, Mar 30 2008


"be prepared to push your trolley off the end of the travelator. oh, and don't hold the handrail as you run"
-- po, Mar 30 2008


There is a constant quantity of custard, in principle. When it reaches the bottom, it is sent back up to the top and the process repeats. There is some wastage, for instance through splashing, sticking to boots, being eaten by pigeons, evaporation, and a small quantity is added at intervals.

[2 fries], it would work in a colder environment if antifreeze were added.
-- nineteenthly, Mar 30 2008


Oui.
Eet eez times such as zeese zat I can nowt help but be an insufferable leetle dilatant eh, no?
-- 2 fries shy of a happy meal, Mar 30 2008


[AWOL] Kindly leave the stage
-- Dub, Mar 31 2008


Sugar is an antifreeze, albeit not the best antifreeze. Custard usually has sugar in it, especially if it is to be eaten.

When the custard is due to be replaced, it can be sterilized and recycled as feed for livestock.

Anyway, + for the mental image it brings.
-- Spacecoyote, Mar 31 2008


I was aware of the sugar situation, but ethanol would also work to an extent, wouldn't it?
-- nineteenthly, Mar 31 2008



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