MOON JUMP

 Bearing a pole and a pack, Miss Heiferton arrives in time to draw then tenth and last turn for the moon-jumping contest. With Angus Le Boeuf presiding, nine other cows make the attempt: Lady Bovine uses a trampoline; Creamella tries homemade wings, and so on, the diminishing row of contestants looking on. None of the amusingly elaborate contrivances works as planned: Dairy Lee's rubber-band helicowpter unwinds too soon; Mary La Moo's mootorcycle stalls. Then Miss Heiferton vaults triumphantly aloft with her simple pole, while her pack turns out to be a parachute to waft her down: ``I want to thank my pole for its support and the moon for being there.'' Brown brings a promising amount of imagination and ingenuity to her first book. In some ways it's over-contrived (the puns are fun, but the verse limps, and kids learning to count to ten aren't going to get some of the sophisticated wordplay) and under-meticulous (if the cows have names like ``Aberdeen,'' ``Angus,'' and ``Jersey,'' they shouldn't all look like Guernseys)--but the idea is unusual, and the brightly colored, nicely designed illustrations have a merry verve. (Picture book. 4-8)