Twelve and six

[Edinburgher]

Twelve and six: No, this isn't about shillings and pence. It's about being straight up and down, or vertical.

I was explaining to someone recently how to top up the water pressure on a central heating system. In particular I stressed how important it was to ensure that the valve which lets the water in is properly shut off afterwards, to prevent the system from getting over-pressurized. This valve does not have a proper knob, but only a slot for a screwdriver (actually the slot is wide enough that it can be operated by "the cheapest screwdriver in the world", a penny coin).

So I told him to make sure the slot is exactly vertical, or else the valve might not be fully closed. "Ah yes," he said, to acknowledge that he had understood, "it needs to be twelve and six."

I understood immediately what he meant, and therefore that he had understood what I meant. This is a clear reference to figures on a clock face, but I was wondering how wide-spread this expression is. I had not come across it before.

Is there a corresponding three and nine, or nine and three, to mean horizontal?

 

[dojibear]

It is pretty common to use clock hours to indicate directions. Often the word "o'clock" is added: "six o'clock".

I don't know if 3,6,9 and 12 are more common than other directions.

Certainly "vertical" and "horizontal" are said much, much more often than "twelve and six".

 

[Hermione Golightly]

I've never heard it and would expect '6 o'clock' since clock hands are often used to show position. "When you're driving your hands should be in the 'ten-to-two' position on the wheel".