--
"Alan McKay" wrote in message

Dont use hydraulic jacks if
your jacking will effect diferent floors

What do you mean? If I don't have a concrete one?
And why are screw jacks better?

Screw jacks are better as you can take up each jack an equal amount. It
took 130 years for the floor to sag. Don't lift it all in a day. I'm not
sure what the recommendations are, but I do know to go very slow and take a
tiny amount each day to avoid cracking stuff.

Is it just a
sagging floor or an unlevel area , how big.

Tomato, TomAHto. Aren't they the same thing?
Most of my main 2 rooms (small house - each room
is 15' x 15' roughly) sags towards a point near the
center of the two rooms

No, it can be unlevel (but straight) from shifting of the foundation or an
error in putting in the foundation years ago. With something unlevel, you'd
want to lift one side as opposed to taking out the sag you have.
Ed