双语+MP3|美国学生艺术史86 彩虹和葡萄酒

  
今天华盛顿的新建筑都是按照朗方少校早年的城市规划和街道设计而设置的，从而使华盛顿成为世界上最宏伟壮观的城市之一。它也差不多是唯一的一座在建造之前就按首都设计的城市。如果觉得拥有这样的首都值得骄傲，那就骄傲吧。因为它值得人们为它感到骄傲。  
86 RAINBOWS AND GRAPE-VINES彩虹和葡萄酒 
  
“Now who will stand on either hand,   
And keep the bridge with me?”  
  
WHEN I was a boy, my favorite poem was “Horatius at the Bridge.” What a thrill I got whenever my father read aloud the story of the brave Roman and his two companions who held back a whole army while the bridge was being cut down to save the city! I even knew parts of the poem by heart, without trying at all to memorize them.  
Horatius at the Bridge; every one knows the story of Horatius. Not so many know the story of the Bridge.  
It was the first bridge in Rome, and when “the dauntless three” stood there with flashing swords and mocked the whole invading army, it was the only bridge in Rome. It was a wooden bridge, one that could be cut down with axes, and it was so important to Rome that it was in charge of priests. We are told that when a new bridge was built, after Horatius and the old bridge had saved the city, the priests themselves built it.  
Have you ever heard the Pope spoken of as the Supreme Pontiff? Supreme Pontiff is one of his titles. Would you ever guess that this title of the Pope came from the bridge that Horatius defended? The chief priest in ancient Rome was called the Pontifex Maximus, which in English means the Greatest Bridge Builder. He was called this because he was chief of those in charge of the bridge. So pontifex, or pontiff, came to mean priest, and that is why the Supreme Pontiff or Bridge Builder is one of the Pope’s titles.  
The pont part of pontiff turns up in another strange use. Try to imagine what Horatius would have thought if he had suddenly seen a seaplane flying overhead, its propeller roaring, its pontoons glistening in the sun. A pontoon is a kind of boat used to hold up a bridge. A bridge across boats is called a pontoon bridge. And so the pontoons that hold a seaplane upon the water got their name because they are like the boats that hold up a pontoon bridge.  
And now I’d better tell you what kinds of bridges there are. There aren’t as many different kinds as you might think. Really there are only five kinds, and that’s a good thing because you can easily learn those five, and then you can name any kind of bridge you see.  
Here they are:  
Number One is the simple beam bridge. A log across a stream is the simplest kind of a simple beam bridge.  
Number Two is the arch. A rainbow would make a beautiful arch bridge, if you could only walk across it. The Chinese have some beautiful arch bridges.  
Number Three is the suspension bridge. A wild grape-vine stem that hangs from one tree to another is a good suspension bridge—for a monkey.  
Number Four has the hardest name to remember. It is the cantilever bridge. If you have a board you can make a cantilever bridge. Hold the board by one end so it just reaches across to the table, but don’t let it rest on the table. Then the board is a cantilever bridge. A cantilever is a simple beam supported at one end, something like a diving board. Often the bridge has a cantilever coming from both banks of a stream and meeting in the middle.  
Number Five is the truss bridge. A truss bridge has its beams strengthened by a stiff framework of different parts fastened together. The framework may either rise above the roadway of the bridge or be beneath it. The frame of a bicycle is something like a truss. Cantilever bridges are often built with trusses. Most truss bridges are built of wood or iron or steel.  
These are the five kinds of bridges. What about pontoon bridges? Pontoon bridges are just simple beam bridges with the beams resting on boats instead of on posts or piers.  
The earliest bridges were, naturally, beam bridges. Xerxes of Persia, a great king, built a pontoon bridge across the Hellespont when he came to fight the Greeks in 480 B.c.  
Strange to say, the Greeks, who could build a perfect building like the Parthenon, were not bridge builders. They traveled by boat more than by road and so they needed few bridges. Then too, the rivers of Greece are generally small enough to be crossed without a bridge, though the Greeks probably got their feet wet in crossing.  
That brings us back to the Romans, the greatest bridge builders until modern times. All roads led to Rome, and the roads had many bridges. Not only in Italy but in Spain and France, in England and in Austria, the fine Roman bridges helped the traveler to get where he wanted to go. Many of the Roman bridges are still standing, are still in use after two thousand years of service. Some were of wood and of course they disappeared long ago, but most of them were built of stones so well fitted together that often no mortar was needed.  
The biggest Roman bridges were not meant to carry people, however. They were bridges to carry water. If you had wanted to take a bath in ancient Greece you would have had to carry the water in jars from the stream or well or else use the stream for a bath tub. But in a Roman city many of the houses had running water and there were also public bath houses where you could bathe in beautiful indoor swimming pools full of fresh, clear water. All this water was brought to town by long aqueducts, stone bridges with a trough on top. These aqueducts went across country for miles from the mountain streams to the city.  
When an aqueduct came to a valley it didn’t go dipping down into the valley and then up on the other side. It went straight across—as a very high bridge indeed. The Romans couldn’t make water pipes very well and so if the aqueducts had gone down hill and then up again, the water would have spilled out at the bottom of the dip. The bestknown aqueduct is now the famous ruin called the Pont du Gard over the river Gard near Nîmes in France.  
After the fall of the Roman Empire, bridge building had a fall too. For years and years during the Dark Ages very few bridges were built. Then in the twelfth century A.D. a strange thing happened. Bridges throughout Europe went back to the care of priests. Only, the priests this time were Christian priests. They formed a society called the Brothers of the Bridge.  
At first the Brothers of the Bridge just kept little inns at river crossings, where travelers might stop. But soon they built their own bridges at these places. Often the Brothers made the roadway over the bridge so narrow at the middle of the bridge that only one horseman could cross at a time. This was to make it hard for robbers and soldiers to dash across and attack travelers. Of course such bridges weren’t much good for wagons, but the roads weren’t much good for wagons, either. Many of these bridges were strongly fortified with huge stone towers at each end, so that they could stop robber bands or even armies from crossing.  
  
NO.86-1　A MEDIEVAL BRIDGE CAHORS，   
FRANCE  
（法国卡奥尔一座中世纪的桥）  
Courtesy of Pratt Institute  
Probably the most famous bridge of the Middle Ages was the old London Bridge over the river Thames. It had houses built on it, some of them four and five stories high, but its foundations weren’t very solid and so it was always needing repairs. Parts of it even fell down at various times. You remember “London Bridge is Falling Down”? At that, it lasted, with many repairs, from 1209 to 1831, when it was torn down to make way for the new London Bridge.  
As you know, after the Middle Ages came the Renaissance, when many famous bridges were built. I’d like to tell you about some of them if I had more space—about the most photographed bridge in the world, the Bridge of Sighs in Venice, and about the Ponte Vecchio in Florence, and about the oldest bridge in Paris, which is still called the Pont Neuf or the New Bridge, and about the Pont Royal and the Pont Marie, also in Paris. All these are stone bridge.  
Modern bridge building began with the railroads, about 1830. At that time iron bridges were built. Then came steel bridges, and finally concrete and reinforced concrete bridges. Reinforced concrete bridges have iron bars inside the concrete to make them stronger. Many handsome reinforced concrete bridges have been built in recent years. Generally, they are arch bridges—sometimes with one arch and sometimes with many. In the United States they are the favorite road bridges.  
  
No.86-2　BROOKLYN BRIDGE OVER THE EAST RIVER, NEW YORK  
（纽约东河上的布鲁克林桥）  
Photograph by Ewing Galloway  
The iron and steel bridges are often truss bridges. In fact, truss bridges are altogether modern.  
Some of the earliest bridges in Asia and South America were suspension bridges. These were hung from cables of rope or vine and were pretty shaky. Some of them are still in use. When you cross one you can’t help hoping you’ll get over alive. Really they are quite strong in spite of being so shaky. But I’d hate to try to cross one on an elephant —or in an automobile.  
Modern suspension bridges are hung from steel cables. Most of them are very large and cost millions of dollars to build. One of the most famous is the Brooklyn Bridge over the East River at New York. Bigger ones have been built since, but this grandfather of modern suspension bridges is still considered one of the finest to look at. It could carry whole herds of elephants in safety. It does in fact carry herds of street cars and automobiles.  
When you go for a trip next time, keep your eyes open for bridges. Many of the finest bridges in the world are right here in the United States. Some travelers play games with bridges as they travel along. In this game a suspension bridge counts 20 points, a cantilever bridge 15 points, an arch bridge 10 points, a truss bridge 5 point and a simple beam bridge 2 points. Sometimes when you go over a bridge you can’t see what kind of bridge it is. All you can see are the railing and the roadway. That would count only one point. Whoever sees the bridge first, gets the points.  
Last of all, I’ll tell you this. All bridges aren’t beautiful, but there are probably fewer ugly bridges than anything else we build; and even ugly bridges generally have an interesting story, if you can find out what it is. One of the ugliest bridges is in Barnstable, England. It has many arches, each one a different size. The size was not planned by an architect, but was determined by the amount of money every citizen donated.  
  
No.86-3　SKY-SCRAPERS OF NEW YORK（纽约的摩天大厦）  
Photograph by Brown Brothers