"Mark Brader" wrote in message
...
In the pictures that I have seen of it, they seemed to be about
the same width as the London trains, perhaps a bit smaller.

Quite a bit smaller. I don't think any photos exist of the interior
of Beach's single car, and drawings may not represent the size
accurately. But here are some comparative tunnel diameters:

Actually, I have a photo of one of the cars and it does show the interior.
There was a PBS special on NYC a few years ago, and the companion book has a
picture of one of the cars after it (and the station )was excavated in 1912.
You're right about the word "system", my poor choice of words. ;-) I guess I
was using it in a general sense.