Only the man who wrote Wild Tigers and Tame Fleas could have written this book. Bill Ballantine is one of those people who simply have to find out all about the things that interest them. Happily for the reader, what interests Ballantine makes for pleasure reading and that peculiarly satisfying kind of information -- the sort that can't be used for very much more than interesting, sometimes startling, conversation. This time around, the subject is horses that work and the men who work them. Ballantine has followed the galloping hoof prints of police and fire horses; the Anheuser-Busch Clydes (right down to how they keep their hair so neat); as well as movie, circus and rodeo horses. The author's interviews with master hostlers and riders is studded with the forgotten, or never before printed, lore of horseflesh at man's labor rather than leisure. One question turned up in the interview of each specialist: What do you think of the intelligence of horses? The depressing news for all those who really believe in Trigger or Silver, is that those in a position to know are not particularly impressed with equine intelligence, which generally leads to anecdotal proof. Once started, the reader is guaranteed saddlesores from his Morris chair before the book can be set down.