--Oscar, in Robert Heinlein's Glory Road
Sometimes a technology evolves to the point where the only improvement is a whole new technology.
Case(s) in point, last week, Pat and I took a mini-vacation to Pennsylvania, to Lancaster and Philadelphia. We visited Pat's cousin, Phil, deep in the heart of Amish country. Pennsylvania has more covered bridges than any other state; 30 in Lancaster County alone.
Covered bridges are the acme of wooden bridge design. Most employ the arched Burr truss --a double arch of laminated timbers combined with a series of triangular king posts. The king posts gave the bridge rigidity and the double arches (one on each side), distributed what engineers call the "live load" (the weight of moving wagons or trucks) to the bridge foundations. The arches are three 4x12 planks made of heartwood oak, steamed to allow a slight curve, and bolted in sections to each other. The seams are staggered so the pieces overlap, resulting in a single load-bearing piece. Most of the covered bridges we saw are still in use by traffic, including honking big farm machinery.
The bridges are made of locally quarried stone with local timber. Wood rots when wet. The builders added a roof, usually tin or shingle, to protect the wood elements and prolong the life of the structure. Uncovered wooden bridges have a lifespan of 10 years; covered bridges go ten times longer, maybe more. Wooden bridges were cheap and quick to build using local labor and were the way you crossed a creek dryshod until the advent of structural steel in the early 2oth century.
The bridge tour was part of the trip to Philly. On the way, we stopped at Strasburg, an early hub of railroading in the Keystone State. Three different railroad museums to choose from; one devoted to toy trains, one to model trains (there is a difference) and one featuring the real deal.
The model train museum, a private outfit, held a layout the size of a basketball court featuring local color. The sheer size of the layout and movement, including aircraft circling on wires, contribute to the biggest sensory overload I've experienced since going through It's a Small World at Disney World. Every 10 minutes or so, the lights dimmed and the houses, streetlights, and cars lit up. Pretty impressive. My favorite, though, was all the small jokes the modelers worked into the set. I saw several, but I'm sure I missed a lot. Jokes like the town square bronze statue of Eisenhower in full uniform with a pigeon on his head.
Or the hobo jungle with a club wielding three-headed troll under the bridge ("my brother is much bigger") the heads were miniature portraits of Larry, Curly, and Moe. There must have been 20 trains running all over the layout including a familiar face.
We saw gentlemen of a "certain age" leaving the gift shop with big shopping bags stuffed with model railroad cars and building kits. A trail of drool led to the door; you could almost smell the lust.
The real deal, however, was the Railroad Museum at Strassburg. I felt the same as when visiting the Smithsonian's Hall of Dinosaurs; big bellowing creatures that evoke the small kid's "Oh wow" response.
Steam locomotives ranging from one used to transport sugar cane in Hawaii to the huge Atlantics and Mikados that ran from one end of the continent to the other and back. A working exhibition train with coal smoke puffing from the stacks and brass bells agong.
Don't get me wrong; I harbor no nostalgia for bygone days. Being an American in the early years of the 21st Century is as good as it gets (on my optimist days) or as good as it ever will be (on my pessimistic ones). But the scent of live steam or the sound of hoofbeats on wooden decking evokes the same feeling as seeing a live mastodon.
When we have perfected aircars and matter-antimatter drive, I can't help but wonder what bits of today's stuff will be considered cool enough to keep.
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Jerry Lamb and I took my two boys and his two boys up to see the train museum back in the late 1980s. I think Josh was 3 and a half. On the trip up, he decided to impress his friend Keven -- same age -- by tossing out a window his copy of The Little Engine That Could.
Our plan was to find a motel close by the Museum. No luck. There was some sort of religious retreat in the area and every room was taken. We did find a Marriott with an ambulance and some cop cars lighting up the parking lot. We asked at the desk if they had any rooms. The fellow at the desk archly replied. "We do now, would you mind waiting a bit."
That was too creepy. We finally found a place all the way back in York. We got two little rooms in a lenolium floored ash trey, each with a single small bed. I slept on the floor and spent the next day pretty stiff.
I was hugely impressed with the great steam engines. I had not realized that you couldn't gang up more than one steam engine. If you needed to haul a big load over a mountain, you needed an engine the size of a 747.
A locomotive is built on a framework of steel that is cast as a single piece, rather than assembled from beams welded together. It took a large foundry to cast a 50 foot long, ten ton engine block in a single pour.
When I took a casting course at Glen Echo, I heard about a foundry that had set up for a pour. They had three cauldrons of molten steel, the two largest were big enough to fill the mold with a few tons to spare. You need the extra steel if some of the mold breaks loose. An extra ton or so can bleed out, forming an extra wing or foot. After they wait a few weeks for the steel to cool down, they cut off the extra extra steel. However, if the block is incomplete, then the casting is ruined.
In this particular pour, huge clouds of steam flew out of the mold, but the steel didn't puddle to the top of the mold. They ended up pouring all three cauldrons. They waited the several weeks. Then they opened up the mold and found nothing but a hole in the floor. The foundry was over an underground stream, one that now holds a 15 ton slug of steel. Must have been fun to watch them pull apart the mold.
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