EVERY SPRING, the Smithsonian tell Washington to go fly a kite. Last year almost 200 adults and children accepted the invitation. This year historian Paul Garber expects at least that many entrants in the Smithsonian's 12th Annual Kite Carnival, to be held Saturday from 10 to 2 on the Washington Monument grounds.

What is the venerable Smithsonian doing out flying kites?

"If you ask me in my official capacity, as historian emeritus and Ramsey Fellow at the National Air and Space Museum, I'll tell you that the kite is history's first form of aircraft," Garber said gravely. "The kite is the ancestor of the airplane, flown by such important scientists and inventors as Benjamin Franklin, Alexander Graham Bell and the Wright Brothers.

"But if you ask me as me," the 78-year-old self-proclaimed kite nut, said with a twinkle, "it's just a heck of a lot of fun."

By order of the Federal Aviation Administration, kites entered in the must not weigh more than five pounds or fly higher than 500 feet - 55 feet less than the Washington Monument.

And if a presidential helicopter approaches, all kites must be pulled down and not re-flown until the helicopter leaves the area.

Novice kite-makers can find several good, helpful books on how to do it, and can buy materials at most hobby stores.

If making a kite strikes you as silly, consider the venerable Ben Franklin, whose kite - made from a silk handkerchief and a darning needle - proved the electrical nature of lightning.

Haughtily tell sneering friends that Marconi raised the aerial for his first famous intercontinental radio linkup by kite, and that Alexander Graham Bell employed a whole factory to built a giant passenger-carrying kite.

The Wright brothers began their experiments into manned flight with box kites, until their invention of the aeroplane relegated kites to their former status as toys.

But don't try to emulate these illustrious inventors by flying your kite in the rain, or by using wire line. Either of these practices may set you up for a big shock.

Don't fly your kite near electric wires, a railroad or an airport. The best places for launching a kite are a flat field, the windward side of a hill or near a large body of water.

Winds of seven to 10 knots (leaves and twigs in constant motion) are ideal for most kites, although a range of five to 15 knots is acceptable for the average kite.

Be inspired by the world kite height record set by a team of 10 boys from Gary, Ind., in 1969. They flew a train of 19 kites for seven hours and achieved a height of 35,530 feet using 56,457 feet of line.

But don't despair if your newly constructed kite has a fear of flying. In ancient China, artistry on kites was an end in itself - so decorate your earth-bound beauty, turn it into a wall hanging and get back to the drawing board.

Or go to the monument and watch, and enter one of the local festivals listed below. Go fly a kite - and have the world on a string!