The Brooklyn Bridge

Exactly what are the Brooklyn Bridge’s towers made of? I don’t know what kind of steel was av ailable in 1883, and Roebling and his colleagues must have furnished something stronger than bricks or stone to support those massive cables. One of my uncles told me that before the 1940s generally, automobiles were made with fabric “hardtops” because solid-steel top manufacture was not perfected until about the time of World War II. (I wrote to Cecil years ago with this question, but got no reply, maybe because the mailbox I put the letter in seems to get robbed a lot.)

the towers are made of stone. the caissions (the things under the water) are also made of stone, I believe. they built them, sunk them, then pumped the water out. To finish them, the workers had to do decompression by coming up gradually… many died of the bends, John Roebling was affected too… his wife Emily supervised the completion of the bridge!

Roebling was a revolutionary in using steel to support his bridge. The cables are made of steel wire, twisted wire together to make steel rope, twisted ropes to make cables, twisted cables to make…whatever is thicker than cables. Also, the bridge was designed to be partially cantilevered.

the way a suspension bridge works is that it distributes force back to the anchors which are on either side of the river – the focus of pressure is not necessarily the tower. At least that’s what I understood.

Quite amazing, I recommend “The Great bridge” by David mcCullough for the Whole story (I read it a long time ago which is why my details are hazy…sorry!)

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The so called “turret top” for automobiles was started in the mid-thirties.

Prior to that a lot,but not all, of them had roof sections of treated materials like heavy canvass etc.

I think my 36 Ford was one of the last with a ‘soft’ top----maybe some of the 37s too.

After you read the McCullough book, may I recommend checking out “The Brooklyn Bridge” directed by Ken Burns on the PBS Video label.

I am not sure, but I think that the actual footing of the Brooklyn Bridge is wood, resting on the bedrock under the East River (not actually a river by the way, I think it is a channel).

The cables on the Brooklyn Bridge are steel rope. By an amazing coincidence, the Roeblings made steel rope. Their own sample failed during testing, and they had to rely on other manufacturers.

And the steel was galvanized to prevent rusting.

The Williamsburg bridge, built shortly after and a little up river from the BB, didn’t galvanize the steel; and in just three years after being built, had to be renovated.

Cables are twisted together to form… larger cables. :slight_smile: (In fact, the biggest ones are called, ‘the great cables’.)


Roebling also over-designed the cables by a factor of ten to one, partly because he wanted to be safe in case he had made a mistake, but mostly because he figured the cable manufacturers would rip him off. (The 1980’s restoration found that he was right!)

John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams