A Bridge Too Few

DAVID PLOWDEN WROTE an engaging and beautifully illustrated article on American bridges (“The Bridges I Love,” Winter 2003), saying a lot in a small space, but in common with other surveys of bridge design where the text emphasizes the tallest, fastest, and longest, no mention was made of the very long railroad bridge across Lake Pontchartrain, in Louisiana. It is the ultimate stepchild of bridge history. I suppose this is because it is so very low and thus not photogenic. But it was the longest bridge in the world when it opened, on November 1, 1883, a 28-mile-long trestle incorporating two drawbridges. It was built of creosoted timbers and pilings by Fletcher, Wisenberg, and Company, of Cincinnati, for the New Orleans & Northeastern Railway (now part of the Norfolk Southern). By the 1890s earth embankments replaced much of the timber fabric, reducing the trestle to less than six miles. A concrete structure replaced the wooden trestle between 1983 and 1997.

John H. White, Jr.
OXFORD, OHIO

A Bridge Too Few

MR. PLOWDEN WRITES THAT he knows of no covered railroad bridge in use today. At Clark’s Trading Post and the White Mountain Central Railroad, a tourist attraction in Lincoln, New Hampshire, a Howe Truss covered railroad bridge is used by wood-fired locomotives that transport guests on a two-and-a-half-mile roundtrip throughout their operating season. The bridge was moved piece by piece from East Montpelier, Vermont, in the 1960s. I worked on it in 1999, helping to replace weathered approaches. We had to jack it up to replace some of the supports—a very interesting job.

Maj. Sgt. Patrick Walsh, USAF(Ret.)
LINCOLN, N.H.

A Bridge Too Few

YOU MENTIONED THE MAS sive Tunkhannock Viaduct, in Nicholson, Pennsylvania. I was born two miles from it and later lived in an apartment almost directly under it. I looked up at it and can only describe the view as colossal. My only regret is that you didn’t include a photograph of it in the article.

Dale Roberts
RIVERSIDE, CALIF.

Birth Of The Hologram

I ENJOY EVERY ISSUE OF Invention & Technology but was especially thrilled to open the Winter 2003 issue and see a picture of Emmett Leith on the contents page and the article on holography that followed (“Holography: The Whole Picture,” by Tim Palucka). In the late 1950s my father, George Wilcox, worked as an electrical engineer in the radar and optics lab at Willow Run. In the summers of 1965 and ’66 I worked as a draftsman in the mechanical-design section of Mr. Leith’s optics group. At the time, the group was split between Willow Run and the University of Michigan campus at Ann Arbor. I made many gofer trips back and forth, the best part of which was the Michiganblue state-owned Fords we used for official business: They looked exactly like unmarked state-patrol cars, and everybody moved right out of the way.

I personally saw the train hologram reconstructed, and I remember it with awe. It was a magic time for me.

Michael Wilcox
SEBRING, FLA.

Wright And Wrong

IN THE “NOTES FROM THE Field” column about Frank Lloyd Wright’s masterpiece (“Fallingwater: Falling Down?” by Benjamin T. Oderwald, Winter 2003), I find much too generous the statement that “Wright was far ahead of his time in his use of materials and methods —so far, in fact, that the demands he placed on the new technology of monolithic concrete construction exceeded the capabilities of building techniques at that point.” Any fool can specify tons of unobtainium to be used in their dream house and ask the engineers to invent it. Frank Lloyd Wright was an artist and a dreamer, but even an artist must know the limits of the materials and methods he specifies. A real architect like Saarinen or Yamasaki, to mention just two, knows how and where to use materials and methods that are, or will be, available, meeting the schedule and cost goals and building a structure that will last longer than called for.

Staffan Persson
MADISON, ALA.

The author replies: Fallingwater has stood for decades in incredibly inhospitable conditions. Though not an engineer, Wright seems to have had an intuitive grasp of structure. His Imperial Hotel in Japan is legendary for withstanding a 1923 earthquake that leveled most of Tokyo. The columns he used in the S. C. Johnson building were held by engineers to be dangerously unsound until a demonstration proved them stronger than anyone had imagined. All structural failures should be as successful as Wright’s.

The Washers Of War

IT WAS WITH A GREAT DEAL of interest that I read the “Postfix” column “Wind-washers” (by Arthur G. Sharp, Fall 2002). I was with the 6th Infantry Division in World War II, and we fought in New Guinea for almost a year. Laundry was a serious problem. Some ingenious men developed a remarkable washing machine. They cut and attached a 55-gallon fuel drum to a truck bumper that had a power winch, and they cut a dasher from a large metal spool that had held field-telephone wire. The drive shaft for the winch was disconnected and attached to the dasher. They would wash your clothes for a small fee in Dutch guilders. Then when we got to the Philippines, the Filipino women would charge a few pesos to take your uniform to the nearest stream, wet it, and beat it to death on a flat rock with a wooden paddle.

Thank you for your remarkable magazine.

Gene Swepston
LITTLE ROCK, ARK.

Primal Patents

I READ WITH INTEREST THE “Hall of Fame Report” on the U.S. Patent and Trademark Office in the Winter 2003 issue (“Patent Magic,” by Jim Quinn). It was indeed the two-hundredth anniversary of the office, since it was formally established in 1802, but you should have mentioned that more than 350 patents were granted in the 12 preceding years. The founding of the patent office was only the formalization of a process that had already been going on. Moreover, you state that about a thousand patents were issued before they started getting numbers (in 1836). In fact the number is about 10 times that.

Philip E. Stanley
WORCESTER, MASS.

The Tube Goes High-tech

REGARDING THE ARTICLE “The Tube Is Dead. Long Live the Tube” (by Mark Wolverton, Fall 2002), what goes around comes around. I was amazed to find recently that manufacturers of motherboards for personal computers are now producing “high end” circuit boards that incorporate vacuum tubes into their sound-reproduction circuitry. The creators of ENIAC would be proud.

Michael J. Mowle
TROY, MICH.

The Tube Goes High-tech

THANK YOU FOR A GREAT article. Having fairly recently completed my studies in the field of electronics, I’ve been exposed only to the solid-state world, with vacuum tubes getting at best a passing mention from the instructor or in an appendix of a book. I will probably never have to fix, much less design, anything with tubes in my career, but it’s very refreshing to have a nice background and history on the subject.

Art Kaplon
CHICAGO, ILL.

The Costly Atom

I WOULD ADD THESE COM ments to T. A. Heppenheimer’s excellent article “Nuclear Power: What Went Wrong?” (Fall 2002). The major reason for the vast increase in the cost of nuclear plants in the United States is the increased complexity of the process of engineering, construction, and procurement of materials and equipment—thanks to poorly conceived regulatory requirements—not increased complexity of the plants. For every hour spent by an engineer doing calculations or a welder making welds, hundreds of hours are spent on paper shuffling to ensure that every action is documented and every instruction recorded and double-checked. Other nations have managed to upgrade their quality assurance without resorting to such needlessly strangling methods.

R. Murray Campbell
COHASSET, MASS.

The Costly Atom

I FOUND THAT YOUR ARTI cle suffered from the same fatal flaw that the nuclear-power industry itself suffers from. It barely mentioned the ultimate problem- the tons and tons of nuclear waste that are generated by plants and that to this day still do not have a final resting place for the thousands of years that they will be highly radioactive and toxic. Until there is a solution to this problem, nuclear power cannot return as a viable source of new power. That is what ultimately went wrong.

Mark W. Davis
BLOOMINGTON, IND.