The people over at the Smithsonian's National Postal Museum call it the Jenny Class Reunion. But there are no drinks, songs or hotel hospitality rooms crammed with loud and aging humans. It is simply a gallery with 23 silent and splendidly preserved postage stamps on decorous display. One of them belongs to the Smithsonian. The others are on loan from generous owners around the country.

To a layman, the Inverted Jenny is just a 24-cent stamp, red with a blue picture of an old-fashioned biplane — but oops! The plane is upside down. To a pilot it pictures an ancient Curtiss JN-4, or "Jenny," apparently at the top of a loop or in the middle of a slow roll. To postal officials it's an embarrassing error that regrettably stumbled into circulation. Only 100 examples slipped past printing inspectors and made their way to the public at the tag end of World War I. All 100 instantly became collector's items. To philatelists, each one is worth about $100,000, depending on its condition. Quite a return on an original investment of 24 cents, though in 1918 for that sum you could buy four glasses of beer with change left over.

"Ever since we were given ours about 30 years ago," says James Bruns, director of the National Postal Museum, "philatelists have planned their vacations around a visit to Washington just to look at it. When they arrive and find it's hidden away, they complain and write nasty letters. But we can't put it on permanent display if we want our grandchildren to see it."

Why? Because of that old museum curator's bugaboo: ultraviolet light. The stamp's perimeter, the "frame," is red, an unstable color. Ultraviolet light would gradually fade it, turning it orange. It's OK, however, to showcase this Smithsonian treasure for short periods. So, in order to atone for past disappointments, and to celebrate the Institution's 150th birthday, our Inverted Jenny is being reunited with those others to provide a feast of philatelic rarities worth more than $2 million. The 23 stamps will be on display at the Postal Museum (Smithsonian, August 1993) from July 30 through September 30.

"This is our first big-time exhibit," Bruns says with pride--and a touch of stage fright. "We have to cope with insurance and security."

The stars of the museum's show are airmail stamps offered for sale on May 13, 1918, in time for the first official airmail flights, two days later. On the morning of the 14th, avid Washington, D.C. collector William T. Robey showed up at a post office on New York Avenue near 13th Street. He was looking for errors and knew that the last minute rush to print, as well as the two-color printing process, would make the stamps especially vulnerable to discrepancies. He knew that stamp collectors would pay high prices for those errors, but he probably never imagined just how high.

Though $24 was serious money back then, Robey decided to get a sheet of 100 stamps. The details of what happened that day are varied, but one version recounted by Robey in 1938 describes how he went back to the post office and asked the clerk if any more airmail stamps had come in. "He brought forth a full sheet," Robey said, "and my heart stood still." The image was upside down! "It was a thrill that comes once in a lifetime," said Robey.

The clerk scanned the sheet but did not hesitate to hand it over. Robey asked if he had more sheets just like it. "At that," says Jim Bruns, "the clerk smelled a rat, and closed his window."

Laying the sheet carefully in his briefcase, he went back to work. There he quickly set about notifying friends and collectors of his find. It wasn't long before a couple of postal inspectors arrived. One of his coworkers, upon hearing of Robey's good fortune, had gone off in search of more inverts and had told postal officials where they could find Robey.

The inspectors were extra polite. Had he just purchased a sheet of 24-cent airmail stamps with an inverted center? "Yes." "Would it be too much trouble to show it to us?"

"Sorry." "Would you be interested in selling it back to us?"

"Sorry." If the expression "No way!" had been in vogue in 1918, it would have sprung to Robey's lips.

Politeness aside, the inspectors then threatened that the government would confiscate the sheet. Robey went home that evening and hid the stamps under his mattress. He knew that official pressure would increase. So he got in touch with some well-known philatelists. One Eugene Klein of Philadelphia snapped up Robey's sheet of stamps for $15,000. Exit Robey, whistling happily. Enter Edward H. R. Green (son of the miserly financier Hetty Green, the fabled "Witch of Wall Street"), who paid Klein $20,000 for the sheet of upside-down Jennies.

Green broke the sheet up, dispersing individual stamps and blocks of four to collector friends. "The condition of some of those stamps has deteriorated since 1918," says Bruns. "Four were stolen; two, recovered. The thief cut off the perforations so the stamps wouldn't be recognized. Perforations are like a stamp's fingerprints, you know. They fit like pieces of a puzzle."

Robey's sheet, ten stamps across by ten down, had been cut along its top and right side. That gave 19 stamps straight edges, nine on the top, nine on the right, one at the corner with both top and right straight-edged. The story goes that Green went to a stamp collector's club, put some of the straight-edged stamps into an ashtray and announced that he was about to burn them. He wanted all present to bear witness to this destruction. The remaining stamps would be the pedigreed thoroughbreds of philately.

"The other members were horrified and made him stop," says Bruns. "So he took the straight-edge stamps home and put them in a safe. After his death in 1936, they again came to light — by then all stuck together." Unsticking them with water removed the gum. Ours is one of those — gumless, with a straight right edge. It's worth about $120,000.

Most printing errors involve either an inverted plate or a sheet fed improperly to the printer. And most are caught quickly, either by a print inspector or a postal clerk. But the clerk who sold that sheet to Robey didn't spot the mistake. Asked about it later, he replied, "How was I to know the thing was upside down? I never saw an airplane before."

In May 1918 the Curtiss JN-4 was one of only a few American military aircraft in full production. Our hope of quickly snuffing out World War I by darkening the skies over France with American-designed "aeroplanes" had come down to this: a lunky training plane, whose prototype had been built in England.

It was awkward and slow, with few instruments. Practical Flying, published in 1918, advised pilots that the best way to avoid skidding or slipping in a turn was to keep an eye on "a piece of string or tape fastened to a strut." You judged a Jenny's airspeed and power largely by listening to the clatter of engine valves and the changing pitch of wind shrieking through the web of wires. The Jenny had wooden skids on the underside of each wingtip to guard against damage in a ground loop — not uncommon because the plane's wheels were about as close together as a flounder's eyes.

When the war was over, the planes went on sale, and many a pilot who had trained in Jennies coughed up $300 or so for a surplus job and took up barnstorming, flying folks for 10 or 15 minutes, charging by the pound for the ride. Pilots found the original 90-horsepower Curtiss OX5 engine dangerously feeble; many replaced it with a Hispano-Suiza ("Hisso"), turning up as much as 150 horsepower. Hisso-powered Jennies were assigned to fly the first official U.S. airmail. Those are the planes on the 1918 airmail stamps, all flying purposefully straight and level except for those 100 aberrations that sputter along on their backs, doubtless spewing a mixture of hot oil and radiator water.

On May 15, 1918, two Jennies loaded with letters were to take off simultaneously from New York and Washington, land in Philadelphia and switch the mail to new planes with fresh pilots (as though at a Pony Express relay station) who would fly on, one to Washington, the other to New York.

President Wilson, scores of dignitaries and thousands of spectators showed up to watch at Washington's Potomac Park. The Washington to Philadelphia flight (Smithsonian, May 1982) soon proved a fiasco. The pilot, Lieut. George Boyle, was fresh out of flying school, where he seems to have studied his fiancée more closely than aerial navigation. Since she was the daughter of the Interstate Commerce Commissioner, political clout got Boyle this pioneering mail mission, guaranteed to chisel his name in the annals of flight.

It did, all right. Hurrying to the field, he barely scanned a road map, then took off, just squeaking over the trees. Sublimely confident, he headed south instead of north. Soon lost, he landed on a soft field 25 miles away, nosed over and broke his propeller.

Two days later, he got a second chance, a new prop and another load of mail. Told to keep the Chesapeake on his right and thus pick up his course for Philadelphia, Boyle obeyed so mindlessly that he turned right at the top of the bay and headed back south down the Eastern Shore, the water of course still to his right. Eventually he reached Philadelphia but picked the wrong field and cracked up on landing. It had taken him three days to fly the 140 miles from Washington.

Despite Boyle, U.S. airmail managed to get off the ground in 1918. Pilots braved dreadful weather, night flights without navigation aids, blind landings, engine failures. Many bailed out, joining the "caterpillar club" or "hitting the silk" successfully. Many died. Today airmail is taken completely for granted. Not so the misbegotten stamps designed to mark its first official flight.

By Edwards Park