I used to jack camps along the waterfront and my advice is to reserch a little bit before you take on this ordeal. You should never have your house setting on just jacks. You need to insert beams 8x8 or bigger we used 12x12s. Insert the beams perpendicular to the floor joists and jack each side 3 to 6 inches at a time using 20 ton jacks. As you lift you need to build cribs for each end of the beams. These cribs support the beam and let you have a saftey incase the jacks give out. You can use 6x6 4 foot long for cribbing.
i just happened to run into this website and got a few great ideas for our old home it was built in 1907.so we do have the same problem it also is sitting on dirt...we just dont know were to being.. helpless in wyoming