Iron was the miracle material of the nineteenth century—abundant, cheap, and extremely useful. It was perfect for jobs requiring great strength in proportion to weight: cylinders for pumps and steam engines; boats and barges for canals; beams and columns for mill buildings; and, eventually, bridges. Several thousand iron bridges were built in America between 1840 (when iron began to replace wood and stone) and 1880 (when it was in turn being superseded by steel); some six dozen survive.

Seventy-one iron bridges from the golden age still stand. They are mostly combination bridges, made of both cast and wrought iron. Here are all seventy-one arranged geographically and listed with their designers and, where indicated, builders. ( NOTE : Several of the bridges listed are privately owned. Owner’s consent should be secured before venturing onto private property.)

BALTIMORE, MD. : When Jacques Barzun wrote, “Whoever wants to know the heart and mind of America had better learn baseball,” in 1954, he inspired today’s pastoral school of baseball writing, in which every pop fly is an evocation of our country’s bucolic heritage. While it’s doubtful that the bleacher bums at Wrigley Field have any such thing in mind when they turn out to cheer the Cubs, Mr.

In 1933, as the Nazis took control of Germany and began to prepare for conquest, one of their first priorities was research into radio communication. Two years later German industry produced a new tool for the trade of listening: the Magnetophon magnetic tape recorder. The Magnetophon was the first truly practical recorder that used tape, and it emerged in the aftermath of World War II to set the modern course of magnetic recording. In America Bing Crosby staked his career in broadcasting to start a revolution for Magnetophon technology.

Brig. Gen. David Sarnoff—chairman of the hoard of RCA, founder of NBC, radio pioneer, adviser to Presidents, and the most powerful and visible man in the business of broadcasting—made three wishes.

When I tell them I invented the personal computer, people look at me like I just stepped off a flying saucer,” says Jack Frassanito, an industrial designer in Houston, Texas. He did invent it, though. His name is on a patent, issued July 25, 1972, for a machine that is the direct lineal ancestor of the PC as we know it.

Sixty years after the world’s first cast-iron bridge was built in England, Capt. Richard Delafield of the U.S. Army Corps of Engineers erected America’s first cast-iron bridge, on the Cumberland Road. The 130-mile portion of the road from Cumberland, Maryland, to Wheeling, (West) Virginia, which opened in 1818, had been built by the federal government as a land route between the Ohio River and the Eastern states. However, as the result of niggardly allocations for maintenance, the road had quickly fallen into disrepair.

“THE HISTORY OF THE ZIPPER?” (BY Robert Friedel, Summer 1994) brought to mind my first experience with a zipper, just before the summer of 1940. I opened a law office in 1938, and in the spring of 1940 I bought a new suit, with a zipper, for $59.50. Connecticut’s blue laws forbade the sale of liquor after 9:00 P.M. on Sunday, and to attract diners, the Seven Gables in Milford, the premier nightclub in the area, had a Sunday dinner from six to nine for one dollar.

“YOU MAY TALK, LADIES AND GENTLEMEN , you may cough. They will not hear you. They do not even know you are here. And now, suppose you all follow me. Just come this way, if you will, and we will meet the first of our temporary visitors.” For forty years millions of revelers visiting Coney Island were drawn away from the clamor of roller coasters and shooting galleries to see these “temporary visitors”—tiny premature babies struggling to survive in prototypical incubators.

THE PHOTOGRAPH ABOVE SHOWS AN INSTALLATION of two IBM 7090 Electronic Data Processing Systems, manufactured by International Business Machines and installed at North American Aviation in Southern California sometime in the early 1960s. In colloquial terms the photo shows a large “mainframe” computer system. The word probably comes from the large metal frames, housed in the cabinets, on which the computer’s electronic circuits were mounted. Entire chassis could swing out, like refrigerator doors, for maintenance.

In December 1848 President James K. Polk told America in his State of the Union address that the persistent reports of gold in California were true. Within days Eastern cities were rocking and humming with a feverish mania unequaled before or since.

“Flashing over the foam, gliding on the wave-tops—Akwa-Skeeing is at once the safest and most thrilling of water sports.” Thus began Fred Waller’s first advertisement for the water skis he patented in 1925. Dolphin Akwa-Skees were said to “glide on the surface of the water behind a power-boat.… You toss the skees overside and step on them while the boat is in motion.” They were sold by Abercrombie & Fitch and Marshall Field and at shipyards.

In the fall of 1958, which was already a year of scientific wonders, plans were announced in the technical and popular press for what promised to be an amazing undertaking. A group of American geophysicists were going to drill a hole several miles beneath the sea floor all the way to the remote interior of the planet—the vast nucleus of dense, compacted rock known as the mantle.

Except perhaps for sumo wrestling, every sport uses some sort of equipment. In some, such as auto racing, advances in equipment are a major part of the sport, while in others, such as basketball, their main role is to separate teen-agers from their money. Somewhere in between these two extremes lies the game of golf.

Learning To Engineer

I greatly appreciate “How Engineers Lose Touch” (by Eugene S. Ferguson) in the Winter 1993 issue of your magazine. I have never forgotten the frustration I experienced as an engineering student in the sixties when I discovered that many of my fellow students, who were doing much better than me academically, hadn’t the slightest idea which way to turn a nut, little intuition about how to put things together, and no feel for materials.

I enjoyed reading the article on interurban trolleys in the Spring 1993 issue (“The Wrong Track,” by George W. Hilton). One of those trolley lines ran from Dayton to Springfield, Ohio, and passed the Huffman Prairie, a cow pasture used by the Wright Brothers in 1904 and 1905 to conduct their flying experiments to make their airplane a practical and useful machine. They knew that Kitty Hawk was only the beginning. One reason they selected this site was that they could get to it by trolley, since there was a station near where they lived, about eight miles out of Dayton.

Long before the Spanish settlers, and long before the Pueblo Indians, a vanished , people built extensive irrigation canals in a corner of the Southwest. From about A.D. 300 to 1400, the Hohokam inhabited the arid region that is now southcentral Arizona, around the modern-day site of Phoenix. Today’s Pima Indians gave the Hohokam their name; it has been translated as “all used up,” “the ancient ones,” “people who have gone,” and similar phrases.

Lafayette, Indiana, in 1859 was by far the largest of the two dozen or so American towns named for the French general. Its nearly ten thousand citizens were proud of their newspapers, their breweries, and their town’s position as head of navigation on the Wabash.

“COME ON IN OUT OF THE MOSQUITOES,” SAYS DANIEL Martinek. He is standing next to a shotgun shack beside a stand of tall loblolly pines. “This is where I spent every day for thirty-five years. It looks like it’s over now.” Inside, line shafting runs down the middle of the single long room; muskrat hangers are suspended along either side. Connected to the shafting are a dozen small machines used in the manufacture of mother-of-pearl buttons. White pearl dust covers everything.

The Interurbans

I enjoyed reading the article on interurban trolleys in the Spring 1993 issue (“The Wrong Track,” by George W. Hilton). One of those trolley lines ran from Dayton to Springfield, Ohio, and passed the Huffman Prairie, a cow pasture used by the Wright Brothers in 1904 and 1905 to conduct their flying experiments to make their airplane a practical and useful machine. They knew that Kitty Hawk was only the beginning.