by DICK FRANCIS
201 pages. Harper & Row. $5.95.
The often shattering and usually infectious joys of the turf are remarkably difficult to describe or explain, especially to outsiders. One of the very few writers who can do so successfully, appropriately enough, is a 51-year-old ex-jockey named Dick Francis.
Before becoming a writer in 1962, Francis was for some years the best steeplechaser in England, eventually becoming jockey to the Queen Mother. He knows the hedges and hazards, the sites and social slights of British steeplechasing the way a car owner knows the dashboard...