BOOKS OF THE TIMES
BOOKS OF THE TIMES; The Invention That Led Sailors Not to Feel at Sea
By RICHARD BERNSTEIN
Published: September 5, 2001
THE RIDDLE OF THE COMPASS
By Amir D. Aczel
Illustrated. 178 pages. Harcourt. $23.
In previous books like ''Fermat's Last Theorem'' and ''The Mystery of the Aleph,'' the mathematician and science writer Amir D. Aczel has amused and edified readers with his clear explications of the profundities of numbers, especially those that led to enduring questions in mysticism and philosophy. In his new book, ''The Riddle of the Compass,'' Mr. Aczel shows his usual accessibility as he explores the origins and significance of the world's most important navigational tool.
There is fascinating material in this new book, not least Mr. Aczel's examination of the decades-old dispute about the identity of the inventor of the compass. His work certainly has temporal and geographical sweep. He deals with the early mentions of the compass by Italian poets of the late 13th and early 14th centuries, and he traces the interesting scholarly detective work that has been done to examine the most standard account of the compass's origin, notably the dubious claim that it was invented as a navigation device by a man named Flavio Gioia from the coastal Italian city of Amalfi.
In other words, there is much to learn in Mr. Aczel's new book. But this volume is less intriguing, a bit secondhand, compared with this author's earlier work. For one thing, the very notion of a riddle seems exaggerated here, an effort to squeeze as much mystery as possible from the subject. Not all interesting questions are riddles, including some of the interesting questions that Mr. Aczel seeks to answer, like where the concept of the directions used in navigation originated, or how sailors navigated before there were compasses.
He does give answers to those and other questions, but much of this book is a summary of already well-known history, like the rise of Venice as a great power and the story of Marco Polo's adventures in China. The writing lacks both precision and the richness of thought and reflection that makes for the best histories of science.
Mr. Aczel begins with some personal history about his childhood spent on ships that his father, a captain, steered to various Mediterranean and other ports, thereby imparting to his son a lifelong interest in navigation. One summer Friday, this interest led Mr. Aczel to a cultural center in Amalfi, where for the first time he was introduced to the idea that Flavio Gioia may never have existed. This leads him to the history of navigation and to the first of several questions he examines: ''How did navigators of antiquity find their way at sea in the days before the compass?''
The answer is interesting and includes Mr. Aczel's persuasive argument that, contrary to common belief, ancient sailors were not coast huggers; they did venture far out of sight of land, and therefore the navigation techniques that they devised -- from observing the flights of migratory birds to knowing the contours of the sea bottom -- were essential. But he doesn't do a very good job of providing sources for his material, and some of his explanations are so cryptic as to raise more questions than they answer.
How does he know, for example, that ''Norsemen discovered Iceland in A.D. 870 by following winds and birds''? What are the historical records for so precise a date and so precise a method? And what exactly does it mean to follow winds and birds? Are there birds that fly all the way from the European mainland to Iceland?
Mr. Aczel shows a good deal more precision when he discusses the interesting controversy surrounding the existence, or nonexistence, of Flavio Gioia, with the evidence stronger for his nonexistence. If the probably mythical Gioia was not the compass's inventor, who was? Nobody really knows. Mr. Aczel traces the earliest written reference to the compass to 1187, in ''De Naturis Rerum'' by Alexander Neckam, an English Augustinian monk. Mentions of the compass by Dante, who lived a century or so later, indicate that by the early 14th century the compass was known well enough to be used as a metaphor in ''The Divine Comedy.''
Mr. Aczel goes back to the Bible to explore the origins of the use of the four cardinal directions. The Etruscans, he says, were responsible for the appearance in the Renaissance of the diagrams known as wind roses, used in compasses to this day. Their Etruscan design, based on divination practices, led to the common 16-point navigation system, each point representing a different wind direction.
A 12-point system, he writes, was devised by one Aristotle Timos thenes, ''a sailor-scholar who lived around 250 B.C. and was chosen by Ptolemy II, king of Egypt, to be the chief pilot of his navy.'' But Mr. Aczel recognizes that the compass was invented not in Europe but in China, though he speculates that it was used there largely for feng shui -- the Chinese art of positioning objects according to the flow of spiritual energies -- and not for navigation.
Mr. Aczel's chapters on China are blemished by inconsistent transliterations and at least one factual mistake: he places the first unifying Chinese emperor, Qin Shi Huang Di, some 600 years before he actually lived and ruled. Yet he does uncover interesting material on China, like the technique devised there for making compasses in the shapes of turtles or soup ladles. But, again without precise documentation, he makes some startling statements. ''The Jesuits, who exerted control in China in the early 17th century, prohibited the reading of books on many subjects, including feng shui.'' It would be a surprise to many historians that the Jesuits were so powerful in China when the Qing Dynasty was at the height of its reign.
Interspersed with such dubiously sweeping statements is interesting information about the development of related maritime technologies, especially accurate nautical charts. But Mr. Aczel spends a good deal of his time giving cursory summaries of well-known historical occurrences: not just the rise of Venice as a world power and Marco Polo's journey to China, but also others like Vasco da Gama's voyage to India. And his main point -- that the compass was a terribly important invention that profoundly shaped the history of the world -- is an obvious one.
''The Riddle of the Compass'' is a worthy endeavor and a modestly instructive one, but it is without the sparkle of Mr. Aczel's previous books.
Photo: Amir D. Aczel (Debra Gross Aczel/Harcourt)