Sorry about this but I know nothing about the organ.
From what I have found on the internet most organs have a pipe or stop called (in English only) the Diapason.
I think I'm right in thinking that the word Diapason means 'through everything'?
Why then is the stop called Diapason, and how does it go through everything?

We never have silly questions here!

The Diapason (also known as a Principle) is the pipe which makes the classic sound of a pipe organ.

The Diapason is the organ's own sound, and does not try to immitate any other instrument. By contrast, most other pipes (stops) try to copy other instruments to some degree. The most obvious examples include the Trumpet, Horn, Flute and Oboe.

You could also have a look at the thread (and links) titled 'An Idiots Guide to Stops?' on this forum.

I hope that helps.

NN

It's not a silly question at all - in fact it's a rather good one.

The answer is in the third article here.

Thanks for that, bit more confusing then I thought it would be though
I need to go and lie down in a dark room for a while

I'm told I'm quite good at imitations?

diapason