Hardy Cross: American Engineer (review)

Hardy Cross was a central figure in American civil engineering. He did not build, but his theories contributed substantially to the rise of the modern framed building worldwide and especially to the spread of the skyscraper. Leonard K. Eaton is not a historian of technology, and this influences a narrative balance in which Cross's family history and early education are more thoroughly dealt with than his professional education and collegial relationships. However, Eaton compensates for this by including an interesting study of Cross's contributions to engineering theory, especially the moment distribution method that made him famous. Written by the engineer and eminent historian Emory Kemp, this is included as an appendix, and it provides an intellectual background to Cross's thinking.

Like Theodore Turak's important William Le Baron Jenney: A Pioneer of Modern Architecture (1986), this work suffers (through no fault of its author) from a dearth of primary sources such as correspondence. It relies especially on accounts by men who were students during Cross's later, less productive years. There are lacunae regarding the influences on Cross and his intellectual development that may never be filled because the material is simply not there. This is no reason to disregard Eaton's book, however, for it provides an account of one of the first internationally important, American-educated engineering theoreticians. There are illuminating anecdotes demonstrating Cross's pedagogical methods and, by implication, his unusual thinking. More of these would have allowed Eaton to analyze his subject's thought processes and perhaps provide insight into how he developed his original ideas. The book is thus useful, but plagued by shortcomings.

Thumbnails of precursors furnish the background on what Cross did. Some of these appear gratuitous and should have been relegated to footnotes. For instance, Stephen Timoshenko's disregard of the importance of the Cross method is tantalizing (p. 42), but it is followed by a page and a half of biographical information where we should have an analysis of the reasons why Timoshenko neglected Cross. There is almost a full page about Gustave Magnel, seemingly because he held a guest lecture for Cross at Yale. Where are the links between these biographies, the engineers' thoughts, and their influence on Cross? We learn that there are such links where Cross attributes earlier thoughts on the principle of virtual work to George Swain. We also glimpse an adversarial relationship between Cross and Milo Ketchum, his dean at Illinois. We learn that Fazlur Khan's thinking on wind forces on tall buildings was possibly influenced by Cross, but how? It would have been good to clarify the relationship between Cross and Karl Terzaghi. We do learn about a characteristic that must have colored all Cross's relations: "Cross, a temperamental genius, did not really work well with the best of his contemporaries" (p. 54). But we are left to wonder whether this, then, was at the bottom of his difficulties with Ketchum as well.

Cross probably never met Pier Luigi Nervi or Robert Maillart when he traveled in Europe, and Eaton indicates that neither he nor his wife "spoke a foreign language" (p. 79). But that should not have impeded a world-famous professional who was curious about eminent colleagues. At Norfolk Academy, Cross had scored high in French and German, and surely this should have given him at least a nodding acquaintance with those languages. What we glean from such fleeting references is the portrait of an eccentric, cantankerous, somewhat deaf recluse who was a genius in his field, but unable to relate to professional colleagues.

One puzzle concerns the paragraphs on the Tacoma Narrows suspension bridge collapse in 1940: "The other consultation in which Cross played a leading role was on the collapse of 'Galloping Gertie'" (p. 60). But then we learn that "Cross's role on the committee is not recorded" (p. 61), and in fact Cross is nowhere mentioned in the official report. Another puzzle is the reference to Pietro Belluschi's Equitable Building of 1948...