Sit down, mind the arm of it, there's a spring under that cushion somewhere and it isn't one of mine. Vernon. I'd shake hands but I've got oil on two fingers and the good rag is in the kitchen.
Right. So this is Mrs Kellsall's, two doors up, the one with the striking. She asked me Thursday teatime and I said yes before I'd thought about it, which is how most things happen. I've never had a clock apart in my life. I got a book out of the library Thursday night and I've read about two-thirds of it properly and skimmed the rest, and I'll tell you straight when I hit the part I skimmed.
The thing nobody tells you, and this is the bit I'm actually pleased about because I worked it out myself on the Friday: there are two clocks in here. Not one clock with a bell on it. Two. Two separate springs, two separate barrels, two separate sets of wheels, sat side by side between the same pair of brass plates and touching each other in exactly one place. That is the whole reason a stripped movement looks like twice the parts it ought to be. It is twice the parts.
The left-hand one is the going train and it does the time. Five wheels and one job. The spring pushes, the wheels gear it down — down and down, about three thousand six hundred to one all in — so that the minute hand goes round the once in an hour, and at the top end of it sits the escapement, which lets exactly one tooth of the escape wheel past per swing of the pendulum. That's the tick. That's it. Everything else in that train is just arithmetic in brass.
And that's the only place in the entire clock where anything is decided. Every other wheel in there is doing as it's told. The escapement is the only part that says yes, one, go on then.
This one's a recoil escapement, which means the pallet doesn't just catch the tooth, it actually shoves the pendulum backwards a hair on every beat. You can hear it. That's why a recoil clock has a heavier tock than a deadbeat does — the tock is doing more work. I sat listening to it Thursday night before I touched anything, which in hindsight was the most useful hour I've spent on it.
Pendulum. This is my favourite bit of the book and it's page 44. The period depends on the square root of the length and nothing else that matters. Not how heavy the bob is. Not how wide it swings, within reason. Not how strong the spring is. So if a clock is gaining four minutes a day, you don't fiddle with anything, you drop the bob a hair on the rating nut underneath it and that's the only adjustment in the whole thing that isn't a bodge.
Hang on. I said "not how strong the spring is" a minute ago and I was wrong, or at least I've said it too flat. The pendulum's period doesn't care about the spring, that's true. But the spring absolutely gets into the timekeeping another way, and this is the hidden problem in the whole business. A mainspring isn't a constant push. It's strongest just wound and it fades all week. So an old movement with no fusee on it runs fast Monday and slow Friday, and a fellow who regulates it on the Wednesday has split the difference and gone in and told himself he's fixed it. He hasn't. He's just picked which day he's right.
Now the other train. The strike. Completely separate spring, its own barrel, its own wheels, and it does no timekeeping at all. None. Its entire purpose is to let a hammer fall a certain number of times. That's the job description.
And at the top of it — this is the one, this is the part I keep picking up — there's a fly. Two little flat blades on an arbor, looks exactly like a toy propeller. First thing I thought when it came out was that some previous owner had dropped something in. It is not a fan. It doesn't cool anything. It's an air brake. Its whole existence is to slow the strike train down so the blows come out spaced apart — bong ... bong ... bong — instead of arriving in one lump as a noise. Something that daft-looking, doing a genuinely necessary job. I've shown it to my daughter twice.
How does it know it's four o'clock? Rack and snail. There's a stepped cam on the hour arbor, like a little spiral staircase, and a lever falls onto it and feels how deep the step is, and that depth is the count. Which means it's self-correcting. You can shift the hands round by hand and it'll strike what the hands say. The other sort, count-wheel, counts slots in a disc and has no idea what time it is — get it out of step and it'll strike seven at four o'clock happily forever until you let it run all the way round. Mrs Kellsall's is rack, thank goodness.
Oh — and this answers something you haven't asked, but I thought of it while I was cleaning a pivot and I'll lose it otherwise. That soft whirring noise a striking clock makes about four minutes before the hour, the one that makes people think it's on the way out? That's the warning. The train gets released partway and then caught again straight off on the warning pin, so it just stands there wound up and ready, and lets go clean on the hour. It's meant to do that. Nothing's wrong with it. I've told two people on the street now.
Before the plates come apart you let the mainsprings down deliberately, with a let-down key, slowly. If you undo a barrel at full power with the pivots not supported the train goes off like shrapnel and you'll strip teeth in the going train that you'll be paying for later. I did that part properly. I was very careful about that part.
The pivots run in plain holes in the brass plates and the holes wear oval, in the direction of the pull, not evenly round. Which is why you get a clock that runs beautifully lying on its back and stops the minute you stand it up. Two of these are oval. I can see daylight round them.
And here I've got to correct myself again, because I said Thursday that a clock with a bad tooth would be losing time, and that's wrong and it was wrong when I said it. A broken tooth in the strike train doesn't touch the timekeeping at all. The clock keeps perfect time and sounds terrible. That confuses everybody, me included, for a whole evening.
Oil goes on nine pivots and nowhere else. Not the escape teeth, not the pallet faces, not near a spring. The most common repair anybody does at home is a good generous soak of oil all over everything, and inside a fortnight that's turned the dust into grinding paste.
Now. The one thing that's annoying me. Somebody's had this apart before me and put a wrong-thread screw into the back plate and burred the hole doing it. And I know it's not old damage because the burr is bright brass sitting under old dirt. Fresh metal, old muck on top. That's somebody in the last few years, forcing it.
Count as it stands: the going train is thirty-one bits including screws, the strike is thirty-eight, and I have counted this towel twice and got eighty-one both times. So there are three I can't place. They're laid out on the right there. I've compared them against the plate at page 61 in the book, which is in the kitchen under a mug. Anyway — that pivot's still not clean.
Have a go if you like. Drag a part in along its dotted line, straight in, it won't go sideways. It'll click when it seats.
It was due back at eleven. I rang her, told her half twelve, she was fine about it.