h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

No, pinnacles aren't hollow. They're just pointy rocks, more or less

Yes, what Mala said. They're just lumps of stone.

weathervanes?

Something to do with the weight, like a cupola helps keep domes together?

Malabarista! I thought you might know. Something to do with weight. DGI +1

they pre-stress the structure making it stronger to resist swaying that could cause failiure in high winds

Then I'll say no more. I do have a somewhat unfair advantage in building questions, I think I know where this is going.

Thanks Mal. That's not it Taff, but you're thinking in the rightish sort of direction.

is it a Key stone or cap stone??

It's not a key stone. They basically just sit on top of the wall, but they do have a practical function.

Is it to create inward pressure to stop the walls of the tower bowing.

That's close McKay, but if you think of where pinnacles are, they can't create an inward pressure.

church walls are buttressed from the outside, does the pinacle put pressure on the roof thats transfered downward by the joists then outward to the walls, aginst the butresses to stop the tower collapsing inward, making it easier to go highter?????

Simpler than that.

it keeps the roof on

No Taff, but it is to do with the roof. Your previous post was closer.

why use oak for buildings????

in a fire, oak beams do not burn fully, the outer layer chars, leaving a strong inner core of wood to support the structure

this exeedes the specifications set down for fire retardation in building materials used today

I didn't know that. Worth a QI +6 I reckon.

Now, back to stone.

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they create inward or downward pressure

they keep the walls on the foundations????

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they create outward or downward pressure

they keep the walls on the foundations????