Welcome to the garage. I'm Sam Ingraham. I fix furnaces and air conditioners for a living, which means I spend all day figuring out why things that are supposed to happen in order don't. This summer my two kids and I spent eleven weeks building a machine in our garage that does the same thing on purpose.

The machine waters a fern. That's all it does. It takes 47 steps, about two minutes, 236 dominoes, a mousetrap, a skateboard, two pulleys, a bucket of sand and the patience of my wife Maryann, whose van has been parked in the driveway since June.

A note on the colors. The kids read everything I put up here, and they don't always agree with how I tell it, so they get to put in their own notes.

JASON: hi. the loop was the hardest step. you will see.

It rained all day on Saturday, June 12. School had been out about a week and both kids were already bored, so Jason dug out the plastic marble run he got for his seventh birthday and set it up on the kitchen table. He ran marbles through it for maybe twenty minutes. Then he said, "Dad, can we make it do something?"

I asked him what he meant. He said he wanted the marble to come out the bottom and knock something over, and that thing should knock something else over, "like in the cartoons." Valerie, who is thirteen and had been pretending not to be interested, said those were called Rube Goldberg machines, and that she'd seen one on a TV show where it took a whole room to make toast.

For anybody who doesn't know the name: Rube Goldberg (1883-1970) was a newspaper cartoonist who drew crazy, complicated machines that did very simple jobs, with a string pulling a lever that tips a bucket that scares a bird, and on and on. He did it so well that his name went into the dictionary for any gadget that does something simple the hard way. He also won a Pulitzer Prize for a political cartoon in 1948, which I didn't know until Valerie got a book of his drawings from the library. We are not anywhere near as funny as he was. But we took his idea and ran with it.

By suppertime that first day we had the marble run knocking over eleven dominoes, which knocked a toilet paper tube off the table. Everybody cheered, including Maryann. Then somebody said, "What if it watered a plant?" and that was the end of our summer.

VALERIE: For the record it was me who said the plant. Dad always tells it like nobody knows who said it.

Why a plant? Because the machine should end by doing a real job, even a little one, and because the fern on the back porch is always dry. Jason named the fern Frank. Frank has been a very good sport.

The machine goes all the way around the garage, starting on the top shelf over my workbench and ending by the side door, where Frank sits on a step stool. We split it into four stations so each of us could be in charge of one. Here's the short version. Every single step is on The 47 Steps page, with what sets off what.

A word about the parts, since people at work keep asking. Being in heating and cooling, I have a lot of leftovers: a length of rectangular sheet-metal duct, half a box of PVC, a coil of the flexible foil dryer vent, and the steel ball out of a blower motor bearing that gave up last winter. Most of those ended up in the machine. My favorite joke of the summer: all the tape holding this thing together is cloth duct tape, and in my trade we don't use cloth duct tape on ducts. On real ductwork it dries out and lets go, so we use foil tape and mastic. But it holds a popsicle stick just fine.

The whole machine was hooked together for the first time on Saturday, July 31. We figured we'd have it working that night. We had it working four weeks and thirty-one tries later. Every one of those tries is in the Failure Log, with where it stopped and what we changed.

By the end of August we'd gotten everything to work at least once. Just never all in the same run. Run #27 got all the way to the last step and poured a cup of water eight inches to the left of Frank, onto the floor. Nobody said anything for a while after that one.

On Sunday the 29th we spent the whole afternoon setting it up. The dominoes alone take most of an hour, and we have a rule now that Valerie checks Jason's dominoes and Jason checks Valerie's. Maryann came out with lemonade and sat on the freezer. At 6:52 in the evening Jason pulled the string.

I'm not going to describe all 47 steps. I'll just say the loop worked, the mousetrap worked, the Elevator didn't stick, and when the sand started pouring into the bucket nobody breathed for about forty seconds. Then the rope went tight, the watering can tipped over, and a cup of water came down right on top of Frank.

I'm not too proud to say I hollered. Jason ran around the driveway twice. Valerie stopped her stopwatch and wrote down the time before she did anything else, which tells you most of what you need to know about Valerie: 1 minute, 53 seconds.

VALERIE: I ALSO hollered. I just wrote down the time first.

JASON: frank was fine. he got wet. that was the point

Since then we've run it nine more times, for Grandma and Grandpa on Labor Day, for the neighbors, and for some of the kids' friends now that school has started. Six of the nine worked all the way through. That's a better average than some furnaces I know.

Friction is everywhere. Every step loses a little of its push to rubbing: wheels on track, the ball on the gutter, the marble against the side of a tube. You can see it. A marble that rolls fine off a smooth plastic ramp will stop dead on cardboard. That's why we can't just keep going downhill forever, and why the Elevator and the sand bucket had to be in there, to put some "height" back into the machine so it had something left to fall with.

VALERIE: The real word is potential energy. Anything you lift up is storing energy, and when it falls or rolls down it turns into energy of motion. The machine is basically lifting things up ahead of time (by us, while we set it up) and then letting them go one after another. My science teacher says I can do the machine for my science fair project if I measure something. I am going to measure friction on the Big Drop with different tracks.

The loop needs more drop than you'd think. Valerie looked it up: even on paper, with no friction at all, the car has to start out higher than the top of the loop, by about a quarter again, or it won't be going fast enough at the top to stay on the track. In real life you need a lot more than that, because of friction and air and wobbly track joints. We raised the Big Drop three times.

JASON: also you cant play with the car. it gets jelly on the wheels and then it stops at the top of the loop. this is a true thing that happened.

A domino can knock over a bigger domino, but not a much bigger one. Our last station is seven "dominoes" cut from 2x4, getting bigger as they go. The kids tested it on the garage floor for a whole evening: each block could knock over one about half again as big as itself, every time. Twice as big, never. So we cut them in steps, from a little one about two inches tall up to one about sixteen.

Heat matters. In August the garage gets up past ninety in the afternoon. Masking tape goes soft and lets go, the vinyl tube in the Corkscrew sagged, and the dominoes didn't care but the people setting them up sure did. We started doing our runs after supper.

Patience. This is the big one, and I want to be honest, it was a lesson for me as much as the kids. Thirty-one times something went wrong. Sometimes it was one domino set a hair too far from the next one and you'd watch the whole thing just stop, and then spend an hour setting it all back up for another try. We had some tears (not mine) (mostly not mine). But every failure told us something, and we wrote every one of them down, and the machine got better a step at a time. Which, if you ask me, is about all there is to fixing anything.

VALERIE: Also we used five of the six simple machines: the lever (the seesaw), the pulley (two!), the wheel and axle (the cars and the skateboard), the inclined plane (practically everything) and the screw (the Corkscrew counts, I asked). We never figured out how to use a wedge. Unless you count Dad's chisel when we built it.

The bad news is the van has to come back in the garage before it snows, and Maryann has been very patient. We're doing one last big run on Saturday, October 16, and then the machine comes apart. We'll keep the Elevator, the Dump Tub and the loop in a box, and the dominoes go back in their coffee cans.

The good news is that Valerie's science fair project is in the works, and Jason has already drawn up a machine for next summer that turns the page of a newspaper. I told him that's a lot of steps for a newspaper. He said, "That's the point, Dad."

If you build one of these with your kids, we'd love to hear about it. Tell us how many steps, what your machine does at the end, and what your worst failure was. Ours is in the log.

Other garage people on GeoCities.us we like: Gene's Inventor's Notebook (gadgets, garage projects and how to apply for a patent) and The Rusty Wrench Awards, which honors home repair gone wrong. I've been nominated in my head several times.