Q: We have a very old radio that we are eager to sell. Would you be kind enough to tell us where to get information as to what it is worth?

A: Write to Burton Katz, a collector of old radios, at Pequod Inc., 8520 Fernald, Morton Grove, Illinois 60053. Enclose a description of your radio and an addressed, stamped envelope for information. A good book that pictures, prices and describes old radios is "Collecting Old Radios and Crystal Sets" by Max Alth, available for $7.95 plus 75 cents postage from Wallace-Homestead Book Co., 1912 Grand Avenue, Des Moines, Iowa 50305. w

Q: I have a Zoetrope toy shaped like a metal drum open at the top, with vertical slits around the sides, made to revolve on a wooden stem and circular base. When a strip of drawings like a cartoon strip is placed within the metal slotted cylinder and the piece is spun on its base, the drawings on the strip give the illusion of animated movement when viewed through the slits. It was given to me when I was eight years old. I am now almost 81 years old old, and the toy was old when I received it. Can you give me any information as to its value?

A: The value of an old toy depends on type, rarity, condition, desirability and features. Some bring hundreds, and even thousands of dollars at toy auctions. Last December at a PB (Parke Bernet) Eighty-Four "Collectors' Carrousel" toy auction in New York, a 19th-century Zoetrope toy like the one you describe, 13 1/2 inches high, complete with 19 cartoon strips, sold for $500. Its selling price was a mere pittance in comparison with the gasping amount that a 34 1/2 inch-long German-made tin toy battleship, circa 1905, named "The Weissenberg," brought. It went for $21,000, although predictions of its price had been only between $6,000 and $10,000. Some other toys brought startling amounts at the auction, which caused collectors as well as investors to sit up and take notice.

If you wish to put your Zoetrope up for sale you may write Pamela Brown at PB Eighty-Four, 171 East 84th Street, New York 10028. Also, illustrated descriptive auction catalogues are available from the same address for $5 postpaid. One can bid from them. A premium of 10 percent is added to the hammer price of each lot sold, payable by the buyer. In addition, state tax is added to the total amount of your bill if Sotheby Parke Bernet has an office or gallery in your state.

Q: In the old days, how did the so-called "ladies of the night" maintain their girlish figures to "stay in business?"

A: They squashed their bodies into extremely tight corsets and bodices that made it impossible for them to overeat, and their diets were mostly liquid foods. Madama Pompadour, for instance, supped on her famous celery soup and also served it to her royal lover. The original recipe for Madama Pompadour's celery soup can be found in the "Centennial Cookbook" along with more than 800 other recipes compiled to celebrate the 100th anniversary of the Union League Club of Chicago by the Women's Board Union League Foundation for Boys' Clubs. It is available in a hardcover edition for $8.95 plus $1 postage and handling (Illinois residents add 54 cents sales tax) from the Women's Board Union League Foundation for Boys' Clubs, 65 West Jackson Boulevard, Chicago 60604. The book also contains reproductions of paintings from the Union Legue Club's extensive art collection, as well as instructions on the art of flaming particular dishes.

Q: We bought a set of six Early American ladderback chairs; several are missing stretchers. Who can make new ones to match?

A: Write to the "man with the golden hands," H. Lanny Green, Antiques and Furniture Restoration, P.O. Box 223, Bensenville, Illinois 60106. Enclose an addressed, stamped envelope for a list of his restoration specialties. He can reproduce many parts of old furniture with such accuracy that one couldn't be able to tell the difference.

Q: Is there a book on buttonhooks? I just started to collect them.

A: Send for a copy of "Antique Buttonhooks For Shoes, Gloves and Clothing" by Bertha Betensley, available for $4.95 plus 65 cents postage from the author at 3444 South Road 1050 West, Westville, Indiana 46931. Another book by this author is "104 Spoon Patents" available for $2.25 plus 50 cents postage. Both books are excellent for collectors.

Q: Can you please supply me with the name and address of the man you once mentioned who buys and collects antique spectacles?

A: Write to Hawley Egleston, 2756 Lincolnwood Drive, Evanston, Illinois 60201. Enclose a description of the spectacles and an addressed, stamped envelope for a reply. Hawley collects antique spectacles, spectacle shop signs shaped like huge pairs of spectacles with a painted eye in each frame, and related items such as lorgnettes, monocles, cases and books on the subject.

Q: Where can I find information about pressed glass candelholders and the companies that made them?

A: Two books that contain such information and that picture in color and price numerous types of glass candleholders are "Glass Candlesticks With Current Values," Books I and II, by Margaret and Douglas Archer, available for $8.95 each plus 50 cents postage for both, from Collector Books, P.O. Box 3009, Paducah, Kentucky 42001. I also suggest you send for a Glass Country, U.S.A. tour flyer by writing to Betsy Ward, 473 Cumnock Road, Inverness, Illinois 60067.

Q: Who would be interested in buying an old World War I uniform and an old army gas mask?

A: Write to Randy Donley at Seven Acres Antique Village, 8512 South Union Road, Union, Illinois 60180.