The Castle of Iron

The Mathematics of Magic was probably the greatest discovery of the ages - at least Professor Harold Shea thought so. With the proper equations, he could instantly transport himself back in time to all the wondrous lands of ancient legend. But slips in time were a hazard, and Shea's magic did not always work - at least, not quite as he expected . . . The Castle of Iron is the second in L. Sprague de Camp and Fletcher Pratt's much-loved Compleat Enchanter series.