" . . . a glorious golden falcon encrusted from head to foot with the finest jewels in their coffers . . . " -- From "The Maltese Falcon," by Dashiell Hammett.

AROUND CHATSWORTH, we always call it 'The Maltese Falcon,' but it's just a joke," said Peter Day, keeper of the Chatsworth Collection. Day may think it's a joke, but hardly any "Falcon" fan could doubt that Chatsworth's Kniphausen Hawk could be no other than the real bird.

Masquerading as the mysterious Maltese Falcon, the bird was sought frantically by the Fat Man, through Hammett's book and the unforgettable Humphrey Bogart, Sidney Greenstreet, Peter Lorre and Mary Astor movie. In the end, the bird disappeared, back into the murky past whence it came.

The Kniphausen Hawk may be one of the most remarkable objects owned by the Duke of Devonshire-- or indeed by anybody. It seems more likely that it was imagined than made.

The bird is 14-3/4 inches high, formed of silver. The beaker and the underside of the base are vermeil (gold plated silver). The body is painted enamel, densely set with gemstones, set in silver mounts: garnets, amethysts, citrine quartzes, turquoises, emeralds, sapphires and onyx. The head comes off. Inside is a beaker. If you were very determined, you could pour from a tube in the eagle's mouth.

Day can't give a stright answer as to just how the Dukes of Devonshire came to own the Hawk. The first time anyone knew they had it was when it made its mysterious appearance at the Great Exhibition of 1851 with a note saying, "Lent by the Duke of Devonshire."

The inscription on the bird says: "George William von Kniphausen, Count of the Holy Roman Empire, Lord of Nienort and of the territory of Vredewold, dedicated this eagle bespangled with gems to eternal remembrance, and ordained that this goblet, flashing with ruby wings and resembling the sign of the ancient family of Ortia, which is now called Nienortia, should remain forever in the possession of the illustrious lords of the castle of Nienort and the territory of Vredewold. This cup was dedicated as a symbol in the year 1697 in memory . . . "

Nienort is a castle in the eastern Netherlands. But the Kniphausen Hawk, as anyone would attest who has seen the "Treasures of Dresden" exhibition (recently at the National Gallery of art here) is more likely the work of a Dresden goldsmith.

Day says there is no documentation at Chatsworth beyond the 1851 exhibit. Speculation is that the Kniphausen Hawk could have been a wedding present. One of those wedding presents that are very grand and valuable, but nobody knows just what to do with.

A torturous connection through various marriages, deaths and entailments, can be followed from the Lord of Nienoord (Dutch spelling) through to the marriage in 1766 of Dorothy, the daughter of the fourth duke of Devonshire, to her kinsman, William Henry Cavendish. (A likely story!)

How the American detective novelist could have found out about the bird is just as mysterious. It isn't the sort of thing the Devonshires leave lying about.

"The Kniphausen Hawk is kept in the vault," says Day. "Except when the Duke is having enough people in to make it worthwhile to bring it out. Then it's displayed on the table in the yellow drawing room."

No one at Chatsworth remembers Hammett coming as a guest. And indeed, it isn't certain he was ever in England, much less Chatsworth.

Otto Penzler, author of the "Encyclopedia of Mystery and Detection" and owner of the Mysterious Bookshop in New York City, always thought the original bird was in the Topkapi Museum in Turkey. But he wrote Lillian Hellman, Hammett's closest friend, and asked her. She wrote back, "Of course you know, Hammett made up the whole thing."

The University of Texas Humanities Research Center at Austin, holder of the Hammett papers, says it has no information on the subject.

"But all you have to do, is to see for yourself. Go down to the Virginia Museum of Art at Richmond, Va., where the Kniphausen Hawk is part of the "Treasurers From Chatsworth" show. As one curator from Richmond put it: "When we took the wraps off it, we shouted as one man: 'We've found the Maltese Falcon.'"

A rare glimpse of the Chatsworth holdings will be given Americans beginning Tuesday at the Virginia Museum of Art in Richmond. "Treasures From Chatsworth, the Devonshire Inheritance" will continue through Oct. 21 before going on for a year's tour of six other cities, circulated by the International Exhibitions Foundation.

More than 250 objects are included in the show.

Portraits in the show are by Rembrandt, Van Dyck and De Vos; paintings by Poussin, Murillo and several of the Italian school. The Cavendish idea of a family portrait was one commissioned by Sir Joshua Reynolds or Thomas Gainsborough.

An exhibition of old-master drawings from Chatsworth was held at the National Gallery a few years ago, but 50 more are in the Richmond show. Included are ones by Leonardo da Vinci, Raphael, Veronese, Durer and Holbein, and a fine collection of drawings and designs for court masques by Inigo Jones.

Over the centuries, the Cavendishes, who originally owned many fine houses, in the countryside and London, have, by the nature of things, had to retrench. As a result Chatsworth has acquired magnificent furniture from former Devonshire possessions: Burlington House, Devonshire House, Chiswick Villa and Hardwick House.

Much of the furniture in the Richmond exhibit is the magnificently carved neo-classical furniture of the mid 18th century. Two mahogany hall chairs in the Virginia show were designed by William Kent, the architect, for the villa at Chiswick. A library writing table of mahogany, walnut and oak from the workshop of Benjamin Goodison, cabinetmaker to the king, also probably came from the Chiswick villa. In the exhibition you can see some of the Goodison chairs in an early 19th century watercolor.

A 1690 walnut, sycamore and rosewood coffer in the show is believed to have been made for the precious documents of the first duke by the Flemish cabinetmaker Gerreit Jensen.

The 23-piece silver gilt toilette service, on loan to the Richmond show, was made in 1670 in Paris by Pierre Prevost. It probably was a wedding present from William, prince of Orange, to the Princess Mary in 1677. The service includes a mirror, candlesticks, powder flasks, an ewer and basin, a covered bowl, a mug, two oval slavers, two caskets, two boxes, two oval boxes, a snuffer tray and snuffers -- all of course embossed with flowers and foliage and embellished with the arms and monogram of the royal recipents.

William III gave the first duke the famous silver service because he knew the duke collected silver. Devonshire commissioned many munificent silver objects from French Protestant silversmith-refugees in England.

After Richmond, according to Anna-Marie Pope, president of the International Exhibitions Foundation, the show will go on to Kimbell Art Museum, Nov. 17-Dec. 31; Toledo Museum of Art, Jan. 19-March 2, 1980; San Antonio Museum Association, March 22-May 4, 1980; New Orleans Museum of Art, May 24-July 6, 1980; and the Fine Arts Museum of San Francisco, July 26-Sept. 7, 1980. The exhibition has been financed by grants from the AMCON Group Inc., HAMBRO AMERICA Inc., the British Council and by a federal indemnity from the Federal Council on the Arts and Humanities. The Andrew W. Mellon Foundation contributed funds for the catalogue.