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That is true, you can check out one of the links below to get the information on the earliest ones from Columbia university. They had lines that were external, with a tube that pushed a block that was connected to the car on rails - but they had problems with too much leakage.

The most successful were the internal ones, both above ground in tube and underground in tunnels. It really became a thing over in England for awhile. But I'll wager many people alive today didn't know about this one underneath the streets of NYC!