Extra ssh jump from whithin host

[Ytsen de Boer]

Dear readers,

 I would like to access files on a computer that is not directly 
accessible from `outside'. I have to log in on one of a bunch of 
computers from which I can, with an additional ssh (no password), access 
the next (`protected') machine.

 How can I, in emacs, use tramp, to edit a file on that second machine? 
What do I type in the `find file' field? I have no problem establishing 
the first connection, but then the extra ssh jump? Or could I make some 
kind of link?

 Any help is very welcome.

 Cheers,

Ytsen.

PS. The point is that I want to edit .tex files on the 2nd machine that 
I want to latex there into a veery big .dvi file. That's the reason that 
I don't move those files to the first machine where I have limited space.