The finale for most shows with lousy ratings usually can be found at the end of a dusty trail that leads directly to the edge of a bottomless canyon - into which the unfortunate show is pushed.

But the finale for a long-running hit is another matter altogether. It can be ridiculously overhyped (Seinfeld) or controversial (Ellen) or muted (Murphy Brown.) But the end of the road for Family Matters? This one goes under the heading of bizarre.

Tomorrow night at 9, when it's guaranteed that absolutely no one will be watching, CBS will air part one of a two-part finale, titled "Lost in Space." Part two airs next Friday - when, again, it's guaranteed that no one will be watching.

What's going on here? Isn't the idea of commercial television to get the most people in front of the set, and not the least? Is, perhaps, CBS so embarrassed that it is obliged to bury it in the middle of July? That seems a stretch. Let us assure you, this Matters' finale will not be the greatest waste of 21 minutes on TV this season; plenty of other shows are competing for that honor. It is an intermittently amusing, if cartoonish, end - nothing much different from the 214 prior episodes.

The show, a Perfect Strangers spin-off that bowed in 1989, originally focused on the Winslows, a middle-class black family. But a few years into its run, neighbor and nerd extraordinaire Steve Urkel (Jaleel White) became the center of attention.

In the finale, Urkel gets a trip into outer space because NASA likes his latest invention (the "Urkel Artificial Anti-Gravity Feed 5000"). He is marooned. He is saved. He nearly gets hitched to paramour Laura Winslow (Kellie Shanygne Williams), but ends the nine-season run with a lingering kiss instead.

So what's going on? The demise of Family Matters - whether you love it, loathe it or have no idea what we're talking about - is a notable event in TV for several reasons. It's believed to be the longest-running show in prime-time television that featured an all-black cast. The Cosby Show lasted eight seasons; Matters, nine. It was, for most of its life - no surprise - a very popular show with black viewers. It also was a very popular show with young kids. The show remains a staple in syndication (reruns air on WPIX/11, TBS and WGN).

The show was never a mega-hit, but it did finish in 15th place among all prime-time shows during the 1990-'91 season. "Durable" may be the best description: never a favorite among critics, most of whom likely never watched it, but a lynchpin of ABC's TGIF lineup, nonetheless.

And then CBS stepped in. Early last year, Leslie Moonves, chairman of CBS Entertainment, pulled off what seemed to be - on paper - a heist. By prying Matters (and Step by Step, another Miller-Boyett sitcom) off the ABC schedule, he hoped to torpedo TGIF by dragging a proven ratings-grabber among young viewers from one flagging network to another. Thus, he could lower his own network's median age (the oldest among the major networks) and attract more advertising dollars. Moonves paid an estimated $40 million for this series, a record for a show to jump from one network to another.

On paper, brilliant. In practice, disaster.

Moonves is a smart guy. What happened here? In a phone interview, he says simply, "It didn't work. It failed. It is probably my biggest disappointment from last year." But, he adds, "the biggest problem facing CBS from the day I walked in here until the day after I walk out is getting ourselves demographically younger. We have no kids watching our network. None.

"My Friday night was my biggest disappointment [because of] the fact that I could take a 16-share show and put it on exactly the same night in exactly the same time period and it goes to an 11 share right off the bat. Yes, I had to pay a little bit higher than I would have liked, but it was our only play in the game. I don't think I should be penalized for taking a risk."

Yet, it didn't seem like such a big one at the time. There is a saying among programers that people don't watch networks, they watch shows. Hogwash. People do watch networks, and older viewers have long gravitated toward CBS. But there also has been a long history of CBS Entertainment executives who have tried to tart up the schedule in efforts to bring youngsters aboard - to no avail.

Matters now becomes the latest victim. A few key stats are telling. The median age of Matters viewers on ABC in late '97 was 32.3. The median age of Matters' CBS viewers was 44.2. The show averaged 14.3 million viewers during its last year at ABC. That fell by 5.4 million at CBS (Step by Step had a similar plunge).

The Family Matters blunder may turn out to be Moonves' single biggest mistake. But why bury this pricey failure in the dog days? Says Moonves, "We didn't know what else, frankly, to do with it."

A final irony: The show that has replaced it, Kids Say the Darndest Things, is doing quite well with kid viewers. It is partly owned by CBS and costs a tiny fraction of $40 million.

I'd like to thank Dirk Oltmanns for sending me this article.