QUESTION: Why is there a hesitation before a soda machine coughs up the goods?

ANSWER: We live in an electronic world and expect machines to behave in chop-chop fashion, like maybe the speed of light wouldn't be too shabby. And yet if you pop 60 cents into a soda machine and hit the Diet Cherry 7-Up button there is always a long pause as though the machine is trying to decide whether it has any Diet Cherry 7-Up left.The thing is, if you intensely crave a Diet Cherry 7-Up, this interval seems to last as long as the Falklands War.

Who makes these machines? Intrepidly we journeyed to the vending alcove of the Why Things Are International Command Bunker, and on the side of the Coke machine found a small metal plate that read: Dixie-Narco. That's a company in Ranson, W.Va. (Kids, yet another possible name for your new garage band: Dixie Narco and the Soda Jerks.)

Dick Bline, manager of engineering for the company, gave us the answers. There are two styles of machines. "Serpentine" is the kind in which the instant you hit the button, you hear the can making noise inside the machine and it appears a second later. This is because a hinged panel has dropped out from under the can and it has rolled down a winding rail.

But serpentine machines are not as popular anymore, giving way to what Bline calls "dual-adaptable" machines that can handle either cans or bottles. And these machines are slower because they are gentler, so as not to break any bottles. The can or bottle rests on its side in a trough. When you hit the button, a motor turns a shaft that slowly tilts the trough to one side, until the can or bottle spills out and rolls down a slanted panel. But in the meantime there's that horrible delay.

We timed it, by the way. Less than 2 seconds.

QUESTION: Why didn't the American Indians invent the wheel?

ANSWER: They did, actually. At least the Aztecs did, if not the more nomadic and less technological "Indians" who roamed what is now the United States. Archaeologists have found toys with wheels among the Aztec ruins - things like little doggies on dollies.

What no one totally understands, though, is why they didn't build big things with wheels, like carts and wagons. They carried stuff on their backs. Or dragged it on sleds. You have to wonder: Were they dense? If those cavemen in the comic strip "B.C." can invent the wheel, why not the Sioux or the Incas?

The academics' answer is that it has to do with animals. The New World had an animal deficit, at least in the category of beasts of burden. In the Old World, the wheel was first used in Sumeria around 3500 B.C., in the form of wheeled vehicles. An essential ingredient was a domesticated animal. Unfortunately, there were no cows, horses or donkeys in the New World. The only domesticated animals in North America were dogs. "The buffalo weren't prone to that sort of thing," says Sam Wilson, an anthropologist at the University of Texas at Austin. "They're kind of more like bears."

We don't find the animal hypothesis totally satisfactory. The Incas domesticated llamas and alpacas. They also had roads in the coastal plains - but they functioned as paths for people and animals. They never built a cart. Nor did they use the wheel for other basic functions - they had no waterwheels, no pulleys. Why not? Certainly not because of ignorance: The Incas and Aztecs were brilliant engineers, building pyramids, cities - even suspension bridges.

The real answer may be that it is presumptious to assume that any culture's technology should follow a fixed pattern, from stone to iron to bronze and so forth. Technology develops according to need, and the cultures of pre-Columbian America did fine without the wheel. The Incas wiped out hunger in an empire of 20 million people even though they didn't even have a very good version of the plow.

So why couldn't an empire of 20 million people repel fewer than 200 Spanish invaders? That's another question - to be discussed later.

The Mailbag:

You may recall that we recently said there was no rhyme for the words orange, purple and silver. Now an annoying person has sent us a page from the Oxford English Dictionary listing the word "curple." It's a Scottish word meaning buttocks. Coming soon to a Scrabble game near you.

Arthur H. of North Miami Beach offers these rhymes:

Restraining a burp'll

Cause your face to turn purple.

Which is virtually "King Lear" compared to:

I smashed my orange

Inside a door-hinge.