SNOWDOMES: by Nancy McMichael, photographs by David Emerick (Abbeville: $19.95; 96 pp.). Collecting snowdomes is an addiction. Believe me, I know. I've got so many my wife won't let me keep them in the house anymore. She thinks they're junk. The laugh's on her, however, because yesterday's toys have become today's collectibles. In this snappy little book, Nancy McMichael tells us what the "snow" is made of (bone chips, pottery flecks, meerschaum sand, ground raw rice, wax bound with camphor in the earliest domes, plastic in modern ones), when they were first introduced (probably in the 1870s) and how the designs changed through the years (domes of the 1960s and earlier were more intricate and showed more hand craftsmanship; from the 1970s on they became cheap, mass-produced knickknacks). You don't need to have a passion for snowdomes to enjoy the book's playful text and colorful photos of more than 200 domes of every shape, motif and era. Now everyone can have an instant snowdome collection, one that doesn't require dusting.