The pencil: lowly, taken for granted, but indispensable to artists and writers, draftsmen and carpenters, architects and engineers. Seems simple, right? Wrong, as engineer (Duke Univ.) Petroski (To Engineer Is Human, 1985) makes clear with a passion in a tome that establishes the pencil as paradigm of design and invention in the history of technology and engineering. Much lore abides here. We learn etymology--""pencil"" derives from Latin ""penicillum"" and ""penis"": brush, tail (no Freudian overtones, please). And history. Mankind struggled with ink and brush, metal points on prepared paper, or true lead styluses until the discovery of a rich source of graphite (called plumbago) in England in the 16th century. The English guarded trade and processing. The French and Germans got into the act anyway, and technology took a leap forward when the 18th-century French engineer Contâ€š devised a way to mix graphite with clay and bake it to create strength as well as blackness. Americans imported pencils until New England craftsmen began experimenting--leading to the Thoreau family business, to which son Henry David contributed ingenious innovations. Petroski's history emphasizes how early technological development was hampered by the rigidity and secrecy of the craft and guild tradition. The industrial revolution and patenting changed that, and, along with discoveries of new sources of graphite in Europe and Asia, led to such pencil dynasties as Faber-Castell, Eagle, Dixon, and Koh-I-Noor (the ""diamond"" of pencils). Read on to learn why pencils are yellow and were named Mongol or Mikado (to reflect oriental sources of very pure graphite), learn about BOPPs (broken off pencil points--the why and how), even learn how to make a pencil. . . Those are the rewards for those willing to pore over what must be the definitive history--448 pages of penciliana--albeit engagingly presented.