What is this?

[Big Little]

What is this?

http://www.hp-gramatke.net/pictures/physics/hydraulic_press.gif

[Qwert]

What is this?

http://www.hp-gramatke.net/pictures/physics/hydraulic_press.gif

This is exactly what the link says: hydraulic press cross-section. If you don't know what is a "hydraulic press", a lot of explanations can be found on the Internet. Here is one: http://en.wikipedia.org/wiki/Hydraulic_press
For the other question on your another thread under the same title, you can find answer here:
http://www.keelytech.com/

[Justsomeguy]

Most likely a paper press. People used to make paper from a mushy goo of plant fibers. This was then spread out on fabric, stacked and pressed to remove the water, then dried. If you look at an old book, like pre 1850 ish , you can make out the weave of the fabric impressed into the pages. But it is a hydraulic press, just like the file name states.