Last night, we had the change from GMT to BST, and as I am looking after our local church clock, I had to go up the clock tower and forward the clock by an hour.
Easily done on your wrist watch…
Firstly, I stop the pendulum
Then I pull the chime lever down to stop the quarter chimes
The hour strike is also stopped
I open the friction clutch on the centre arbor. This separates the movement from the centre arbor, so I can turn it to adjust the time
As the outside hands move clockwise, the hand on the setting dial moves counter-clockwise. I move the hand with the setting key until the hour chimes and the strike have set off. That's why I stopped the strikes - I don't want to confuse the whole village
As the strike sets off, I have to make sure that the air brake doesn't hit my hand as I have to keep the hand supported with the setting key
Now that I have forwarded the clock by an hour, I put the setting dial on two minutes before the next hour
Now I close the friction clutch with a small hammer
I go down the ladder and restart the clock by pulling the pendulum towards me and then letting it go
Now I wait until the clock strikes the full hour. As I had set it to 2 minutes before the next hour, that’s how long I will have to wait. First, the quarter strike goes off, and as soon as the first hour strike strikes, I stop the pendulum again.
As the clock doesn’t have a second hand, this is the only way to make sure I have the clock exactly at the full hour.
All I have to do now is wait with an exact time source in my hands (I use my android phone, on which I have an ntp client), and start the pendulum again at exactly the full hour.
Voila – our church clock is now on BST.