Q. We recently moved into a old home that we plan to furnish with country-type antiques. Our friends gave us an old horseshoe to nail on the door for good luck. What is the proper way to hang it -- with the prongs up or down? Also, should it be mounted on the outside of the door or on the inside? A. An old horseshoe should be mounted on the outside of the door with its prongs or open side pointing upward, forming a pocket of luck to draw and destroy the devil. If a horseshoe is mounted with its open side down, all the luck would run out. Horseshoes also are believed to repel witches, demons and evil influences. q. Where can I get wooden top such as the ones we spun as kids years ago? Your cooperation will make my grandchild happy. A. Occasionally, old wooden tops can be found at antique toy shows. However, places that make and sell wooden folk toys and tops include the following: The Toy Factory, 88878 Coast Hwy. 101, Florence, Ore. 97439 (enclose 50 cents for its 30-page catalogue); Berea College Student Craft Industries, CPO 2347, Berea, Ky. 40404 Enclose 50 cents for its 28-page handcraft catalogue). There also are reproductions of old-fashioned tops made in Taiwan by Lion Rock, Ltd., which can be purchased for around 58 cents each at the various Toys "R" Us locations. Q. I've been collecting marbles for years. Is there a book that can tell me more about them, such as age and value? A. Send for a copy of "Collecting Antique Marbles," by Paul Baumann, available in a hardcover edition for $8.95, plus 75 cents postage, from Wallace-Homestead Book Co., 1912 Grand Ave., Des Moines, Ia. 50305. Another $1.50 will get you the corresponding price guide which gives the value of antique marbles. The book also is available from Tiny Treasures, Rural Route 2, Box 141, Oswego, Ill. 60543. Also, if you're interested in joining a marble collectors club, write the Marble Collectors' Society of America, Box 222, Trumbull, Conn. 06611. Dues cost $10. Q. Is there an organization for collectors of matchcovers? A. Write to the Rathkamp Matchcover Society, c/o Isabell Lord, secretary, Box 8487, Long Beach, Cal. 90808, and enclose a self-addressed, stamped envelope for information. Founded in 1941, this society has 900 members and publishes a bi-monthly bulletin. You can join for $3. Q. Some time ago, a coin auction held near St. Louis sold a rare Brasher doubloon to a Chicago coin dealer. Please give me his name and address because I'd like to contact him about some rare coins I have. A. Write to Walter Perschke. c/o Numisco Inc., 175 W. Jackson Blvd., Suite A-640, Chicago, Ill., 60604. Q. Could you give me some information on local barbed-wire associations for collectors? I have some barbed wire and would like to identify its type and manufacturer. A. You can write to the International Barbed Wire Historical Society, c/o Jack Clover, Sunset, Tex., 75270, or Texas Barbed Wire Collectors' Association, 1019 Cedar Trail, Tex., 75104. Enclose a stamped, self-addressed envelope.