Adult things are hateful and unnecessary - just ask any child. When we were kids, whatever grownups considered useful and worthwhile we thought was tedious and boring. You didn't split lumber with a saw, you jumped up and down on it and smashed it to smithereens. You didn't pound nails with a hammer, you beat them to death with a rock. Tools were just dumb; you could tell by the way older persons became crazy when they couldn't find them.

So we never dreamed of using a ladder for anything, especially not the tree house. We either climbed up, hand over hand, because that was difficult and fun, or, on big oak trees especially, we drove pieces of scrap wood into the trunk with nails the size of railroad spikes. You knew you had a good tree house when there were so many twisted, rusting, bent-over nails in the wood they looked like worms. The steps turned like windmills underfoot and made you fall anyway.

Some should conduct a study to find out when it is that kids start appreciating adult things like ladders. If we knew that, we could start doing something to stop people from becoming adults and creating big-person problems. The adult persons I know would never think of pounding pieces of scrap wood into the side of their house to get on the roof. Most of them are pretty unhappy, too.

Yet, innocence is a thing easily lost and sometimes we try to be more practical. Like the time the landlady steps out of a Sunday aftertnoon and there you are with the kitchen faucet fallen off and water three inches deep in the living room and rising. Of couse there's no ladder around and you have to scale the front of the house to get into her apartment on the second floor to find the main valve.

Ladders are also useful for reaching such heights in the kitchen so you can write your name in the dirt on top of the refrigerator. Or to check if the leaves in the gutter have turned to compost yet.

Moving up in the world is a generally desirable thing. But many people apparently don't pay enough attention to how they get there. The Consumer Product Safety Commission estimates nearly 70,000 Americans were treated last year in hospital emergency rooms for injuries resulting from poor use of ladders. The commission even breaks injuries down into types of ladders people like to fall off most: Stepladders, 8,630. Step stools, 8,913. Straight ladders, 1,145. Extension ladders, 1,118. The majority, 49,448, didn't say what kind of ladder it was. Perhaps they felt a little foolish.

Ladder manufacturers don't want you to fall of their ladders. For one thing, accidents can lead to product liability suits that ladder makers would prefer to avoid. Prospective ladder buyers will find most models plastered over with testing seals and warning labels. That's just the maker's way of saying "be careful."

Not the least of ladder hazards, says Warren Stevens, safety instructor with the Montgomery County fire department, is receiving the shock of your life from electrical wires around the roof. Metal ladders, the biggest sellers in recent years, are especially vulnerable. But even wooden ladders, Stevens says, can counduct some electricity because of the moisture they contain. Try to locate your ladder away from wires.

Before climbing up on a ladder, inspect it for loose joints, cracks and rotted rungs. Position the base of an extension ladder on a level surface. You can tell the neighbors how you climbed 40 feet with the ladder balancing on one foot, but only if you make it back down alive. The base of the ladder should be away from the wall a distance equal to one fourth of the ladder's height, or so that it leans at about a 70-degree angle. When they reach a vertical position, extension ladders tend to fall in the opposite direction you hoped they might.

Sandals are a poor choice of foot-ware on ladders. Non-slip soles are best. If you are further disinclined toward acrobatics, do not stand on the top of a ladder or on the top two rungs. Have a friend hold the ladder while your're on it. Sharing things can save energy, such as the gas you might use traveling to and from the hospital.

And when arrive at the top, tie, the ladder to something secure, not a gutter that should have fallen off yesterday.

You can buy a ladder almost anywhere. Some are better, and more expensive, than others. Look for an Underwriter's Laboratory (UL) label to be sure the ladder meets testing requirements. Many ladders also carry a label from the American National Standards Institute (ANSI). The ANSI label is a "duty rating," says Jerry Brase, the paintwares buyer for Hechinger Co., and divides ladders into three types.

Type 1 ladders are generally sold for industrial use. They are the most expensive and sturdiest, with a listed load capacity of 250 pounds. Type 2 ladders are aimed more at the commercial market, with a weight limit of 225 pounds. Type 3 ladders are designed for home use, recommended for up to 200 pounds, Brass said.

Hechinger sells several types of ladders, from 26-inch stepladders to 32-foot extensions. Prices range from $15 for the smallest to $30 for a platform ladder, $80 for a ladder that can be converted into a two-man ladder or an extension ladder or for use on stairways, and up to $130 for the longest extension ladders.

Sears sells a 40-foot extension ladder for $190 and 16-footers for $50 and $33. Its stepladders come in 5-, 6-, and 8-foot sizes at $22-$45. Montgomery Ward's 28-foot extension ladder sells for $110, its 14-footer for $28. Aluminum stepladders at Ward's are $30 for the 5-foot size, $37 for the 6-footer. Wooden stepladders are $22 and $26 for the 5-footers, $27 and $31 for the 6-footers.

Many equipment rental services rent ladders for around $8-10 a day. Remember that the extension ladder you buy or rent should be at least three feet longer than the distance you want it to reach.

You don't need the most expensive to be safe, says Brace. "A customer should not let someone con him into buying a $300 ladder that he has absolutely no use for." But check safety features: Among these are: extra support under the rungs, I-beam construction, braces that lock and are not flimsy, rungs that are grooved for extra traction, free-swinging swivel feet to hold the ladder firm and no sharp points to scratch paint or snag clothing.

About $17 buys a ladder stabilizer that spreads weight more evenly from the ladder to the house.

If you already have a stepladder but no use for it, don't throw it away. It makes an excellent stand for house plants.