Tuesday 16 September 2014

Going Round in Pedantic Circles

It's well known among pedants that spiral staircases aren't spirals at all, but helices. A spiral staircase, apart from not needing any stairs, would not take you through the "y" dimension, without which a staircase is pointless. You'd just go round in ever-decreasing circles, on a spiral staircase. In other words, and at the risk of labouring, straining or overstating the point, spiral staircases are badly named. And helical staircases, even when correctly designated, are a bit common.

That's why the new Moot House has a double-helix staircase.

You could say innovative architecture is in our DNA. Or possibly vice-versa.


  1. Does Helix have something to do with Felix the Cat? Perhaps his brother or sister?

  2. Of course, if your spiral is a vertically-orientated one (i.e. your r-theta plane is vertical, rather than horizontal) then you COULD make a spriral staircase; but, unless you are good at walking upside down, it is best only to use the very small section of the spiral. For an Archimedian spiral (r = a + b theta), I would advocate using a part where theta varies by no more than pi/2 radians and choosing a to be larger than b.

    The resulting staircase would climb in a graceful arch, which could be either convex or concave depending on your choice of the range of values of theta.

  3. PS. As a pedantic mathematician, I would like to suggest that it is more usual, when working in 3-D, to consider the x-y plane to be horizontal and for the vertical direction to be designated "z".

  4. Stop plagiarising Leonardo da Vinci! He invented the double helix, long before Crick and Watson and that woman chemist everyone keeps forgetting (not you, Archdruid!), and had one built as a staircase at the Château de Chambord.


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