HER MAJESTY the Queen of England, may her tribe increase, has just lent us 50 fifty! Leonardo da Vinci drawings from the Royal Library at Windsor Palace.

We've had several chances to see some of her Leonardos in recent years, but this time she has sent us half a hundred all at once. They're said to be the best of the 92 horse and other animal drawings among the six hundred of his works at Windsor: In other words, the finest such Leonardos in the known world.

The exhibition, which opens Sunday in the National Gallery of Art's West Building, is heady stuff in more than one sense. It's brain-bruising to try to take in so many Leonardos at once, and because most of the works are rather small, you'll need to bend close to see them clearly in the necessarily dim light. At which point you'll probably bump heads with some other Leonardo lover.

The low light avoids further bleaching of the images, some of which have faded badly over the course of half a millennium. But most are in "amazingly good condition," said the Hon. Jane Roberts, curator of the crown prints. "One of the wonderful things about Leonardo is that he chose very high- quality paper."

Another amazing thing is that the prints haven't been scattered all to hell and gone, because Leonardo's genius was recognized by his own generation as well as all succeeding ones. Leonardo (1452-1519) bequeathed his drawings, books and papers to his favorite pupil, and the next owner bound the prints into a single volume. The book may have been in the custody of fewer than a half-dozen people before it wound up, by 1637, "in the hands of the King of England."

King Charles lost his head in 1649, and subsequent British monarchs have lost everything from crown jewels to the Colonies, but none has let go of any Leonardos. They would hardly even let them out of the castle, much less the Realm, until recent advances in the art of art conservation made it possible to ship and show the works safely.

Better yet, recent advances in the arts of photography and printing have made it possible for anyone to have more legible Leonardos than the Queen, God bless and keep her and her heirs and assigns forever. In many cases, pictures of the prints are clearer than the originals, and show the shadings and textures better. Ultraviolet imaging has brought back splendid details and whole drawings that no longer are visible to the naked eye.

Take the catalogue ($17.50) home and you can look them over at leisure, and you won't be beheaded should you spill coffee on one. Get a second catalogue to cut up; most of the illustrations are of mounting quality.

Horses dominate the drawings because horses dominated Leonardo's time. The horse was the principal means of transportation, the only major portable power source, the heart of commerce and the engine of war. Beyond that, the master was a lover of horses, according to Gretchen Hirschauer, the National Gallery's assistant curator of Italian paintings.

"I was stunned by the drawings," she said. "I have loved horses all my life, and own two of them. I believe Leonardo must also have loved as well as known horses, because these drawings express feelings about them, not just their anatomy and energy."

Animals yielded to the master's will as readily as did everything else to which he turned his attention, with one conspicuous exception that is somehow comforting to a mere mortal: Leonardo, as these works show, couldn't draw cats for beans.

LEONARDO DRAWINGS FROM THE ROYAL LIBRARY -- Through June 9 on the ground floor (Seventh Street entrance) of the West Building, National Gallery of Art. Archives or L'Enfant Plaza Metro stations.