I have jacked up several parts of my 1925 house. What I have found to work best is to use 6-10 ton bottle jacks w/ 3 2x4's nailed togeather for a post(DO NOT USE 4x4 IT WILL CRACK) apply one bottle to each side of the beam you made to put under the floor joists (3- 2x8's nailed togeather every 8").
Use the bottle jacks to lift the house once to heigth, then use regular basement poles to provide extra saftey under beam. DO NOT REMOVE BOTLE JACKS.
Any more questions feel free to contact me: dwalker@stonesimons.com