BY HENRY PETROSKI

Two of our greatest engineers coped with failures.

The birth of two engineering giants will be celebrated in the year 2006, and all 21st-century engineers can take great pride in having them as professional antecedents. These heroes exemplify the pioneering spirit of those who work on the technological frontier somewhere between success and failure.

John Augustus Roebling was born in Mühlhausen, Saxony, on June 12, 1806 and emigrated to the United States in 1832. The course of his life from an idealistic farmer to a pragmatic designer, manufacturer and builder is widely known, having been chronicled by David McCullough in his story of Roebling’s crowning engineering achievement and masterpiece, the Brooklyn Bridge.

What drove Roebling is what drives so many engineers—a dissatisfaction with things as they are and a fascination with technical challenges to improve the world. Such personality traits often coincide with opportunities for the engineer/entreprenuer. In Roebling’s case, the unreliability of hemp rope used to haul barges up inclines led him into the wire-rope business. Like any manufacturer, he wished to expand the market for his product, and he was drawn to designing and building suspension bridges.

At the middle of the 19th century, suspension bridges were infamous for their susceptibility to wind damage. Roebling looked upon the many flawed suspension bridges of the era not as mere examples of failure but as unintended experiments. He found in the data of case studies a common cause for the failures, namely excessive flexibility in the wind. By prescribing relatively heavy and stiff decks for his bridges, he was able to build wind-resistant structures. Roebling’s genius lay, at least in part, in his ability to fashion success out of the lessons of failure.

Failure also played a role in the career of Isambard Kingdom Brunel, who was born in Portsmouth, England, on April 9, 1806. For his engineering education, Brunel was sent to France, from which his father had fled to escape the revolution. Returning to England, the young Brunel got his first practical experience by working with his father on the Thames Tunnel. After being injured on the job, young Isambard was spending time recuperating near Avon Gorge when a bridge-design competition was announced. His entries did not succeed, but after his death, the Clifton Suspension Bridge, which was built based on one of his designs, became a memorial to him.

During his lifetime, Brunel was the engineer of many structures, including bridges on the Great Western Railway, which is generally considered a masterpiece of railroad alignment and design. He also designed its original terminal buildings in London and Bristol, as well as its Box Tunnel. Not satisfied with providing a means of transportation to the Southwest, Brunel also designed steam ships to travel across the ocean. His Great Western was very nearly the first ship to cross the Atlantic under steam power alone, and his Great Britain was among the first to employ a screw propeller.

For all of his successes, Brunel was also dogged by embarrassing failures. These included his atmospheric railway, in which a partial vacuum was employed as a means of propulsion, and his preference for the broad gauge of the GWR, which ultimately had to be replaced by the standard. His leviathan Great Eastern remained the largest ship built for 40 years, but it had got hung up during its launch—killing one person and injuring four others— and ultimately proved unprofitable as a passenger vessel. In spite of all this, Brunel is possibly the most revered engineer of all time, respected for his successes and allowed his failures. In Britain, he is known by all and was recently voted the Greatest Briton after Winston Churchill. Unfortunately, in America, too many people struggle to recall even the name of the engineer who designed the Brooklyn Bridge.

Henry Petroski is the Aleksandar S. Vesic Professor of Civil Engineering and a professor of history at Duke University. He chairs the History and Heritage Committee of the American Society of Civil Engineers, which is sponsoring a Roebling Bicentennial Symposium and tour Oct. 27-29 (see www.asce.org/conferences). He is also a corresponding member of the Panel for Historical Engineering Works of the Institution of Civil Engineers, which is sponsoring a week of Brunel bicentennial events July 3-9 (see www.ice.org.uk/conferences).