Install a rooftop turbine? We give it a whirl.

The instructions on the box looked easy. Three steps, each requiring only one short sentence, the last part of the third being, "and you're done." Well, we'd long wanted - let's say I'd wanted - to get one of those whirlybird turbine things that spin around on the roof and vent the attic to help keep the house cool.

They look so shiny and busy up there, twinkling and twirling on other people's roofs. We'd managed to postpone this small home improvement project for 25 years or so, through two arduous re-roofings, but here was a turbine at a garage sale for $10 and still in the box.

We took it home and put it in the shed. For six months it was too hot, too wet, or too daunting to deal with.

Last Monday, sitting in the garden, I ruined an overcast but otherwise perfectly good morning by bringing up the subject of the turbine and bringing out the box.

Inside the box, it turned out, was another set of instructions, the "evil brother" version, with many words, eight pictures, and two diagrams. All of it presumed facts about the roof that were not true, in our particular case.

We sat with the directions and the metal parts. We put them side by side on the lawn, in an effort to persuade them to try to get along. No good. Chaos theory reigns, and fractals bloom in the garden. We decided to ignore the extra instructions and go with the three-step system. (We are brazen at times.)

No. 1. Cut a hole in the roof to fit the sleeve.

Well. To do that, you'd better know where the rafters are. This means crawling into the attic, along the edges of joists, amid clouds of insulation, trying not to put a foot through the ceiling.

I haul myself through the small trapdoor and balance my steel ruler on a ledge, but it takes a dive into the space between the studs. I can see it, 10 feet down in the dust. (We've been through a lot together, that ruler and I. It's got my name on it from my days of adult ed. woodshop, the only woman in the class. I'll get it later.)

As the insulation flies around me like feathers, I remember when we used to have to pluck our own Sunday supper. I think what's in my mind is how much "Whirlybird" sounds like "Willie Bird," the local turkey farm. For now, I just count rafters: 14. An even number means we can make our hole in the middle of the roof's length.

Later, back on top of the roof and drill in hand, I think, "...doesn't it?"

Yes. First you have to cut through the asphalt shingles, two layers. The asphalt sticks to the saw blade while the shingle grit dulls it, an efficient enemy of our 1/17th-or-something horsepower jigsaw - about one mouse power. Eventually, though, we nibbled our way through and have a crazily circular hole. I poke my head through, feeling like Schliemann excavating Troy, but find no gold.

No. 2. Install flashing and attach sleeve.

We nail the flashing in place, half under, half over the roofing, as required - well, all right, upside down at first, but we correct this. We nail, mastic, and caulk as we think fit. We make many trips up and down for additional tools; creeping along the roof's peak, down the side of the dormer, in at a bedroom window, then down the stairs, through the kitchen, and outside to the toolshed. The last trip is for a single long nail, needed to break the seal on a tube of caulk. The metal screws in the kit don't fit, but we have others, and soon (well, not really soon) the vent is level and whirling smoothly and silently, just like the ones in the movies.

I'd like to add ribbons, pink and lilac. I don't mention this. Restraint is hard for me because it necessarily must go unrewarded. I need those little gold stars we had in school, proof of virtue.

I've forgotten what Instruction No. 3 was, except for that last part: "and you're done."