I can't answer your questions, but when you are feeling down and out in your house journey, try reading The Devil Queen blog by John in Arkansas. Of the old house blogs I've read, he skated closer to the edge financially than any other I've seen. Don't want to be a spoiler, but you'll be glad to know he lived to tell about it. :-)

Could you put a lolly column under each splice (yes I know it'll ruin your first floor layout), tell the inspector you're into industrial mod and you love it that way, then take them out and sell them on craigslist after it passes inspection?

I understand the need for the government to intervene in our properties so that you can walk into a building, any building, in this country, and feel pretty sure it won't collapse on you, but the libertarian part of me bristles. Especially with the "if you remove one switch plate cover for 5 seconds, you have to rip everything out and bring it all up to code" trap.

Here is a link that might be useful: Ahh, the Devil Queen

You are likely going to need an engineer experienced with old wood frame buildings to look things over.

A stamped drawing usually satisfies the AHJ (they are rarely engineers anyway).

If the joints are adequately fastened you might not have that much of a problem.

At least part of the trouble is that even the lumber sizes have changed over the years, along with grading standards.
That make the 'per se' portion of the code inapplicable.

The span tables are based on grade of wood and actual size (though given as nominal).
With no grade information it can be difficult to decide what is adequate.

One clue is how bouncy the floors feel.
If they feel solid you might get away with minimal sistering.
If the have a lot of bounce or sag it gets harder.

Well, it's survived this long...
The proper thing to do is add two more mid-span girders so that all of the splices are supported. Is the existing mid-span girder under a wall above? If the answer is no, you could remove it after you put in the two others. The new beams will need posts and footings to transfer the load to earth.
Just exactly what these loads are is something that we can't say or take into account on the interwebz. You need to see Mr/Mrs "structural engineer".
The cantilever/splicing was not a good idea to begin with.
Casey

"The cantilever/splicing was not a good idea to begin with. "

Works fine if designed correctly.
Adequate size and nailing pattern for the load.

Not reading closely, I saw this as a basement level ceiling. OOps. My solution would not be any good.
If the whole thing is opened up, you'd do well to add a round of new fasteners, like "Headlock" or "Spax" screws, if not 1/2" bolts and washers. 2 screws every foot should be more than adequate across the length of the overlap. If bolts, half as many. Clamp together before bolting so the members are drawn tight. If any of these two-part joists have sagged relative to their neighbors, I would try subtle jacking to take out the drop.
Well, Brick, no inspector today would pass a system like that, you and I know that, without a stamped drawing. That's just seat-of-the-pants ad hoc carpentry, standing in for the proper material. If they had access to 24' joists they wouldn't have scabbed it. And it's not like extra-long lumber wasn't available; worked on a 1896 house this winter with 32' 3x10 joists. Thirty-two freakin' feet of SYP!
Casey

"if not 1/2" bolts and washers"

3/8 is really the largest that will not quickly exceed the crush rating of most framing wood under load.

And yes, that means you need more if them and preferably NOT aligned with the grain of the wood.

If the grain is straight stagger the bolts, if the grain runs diagonally put the bolts in a straight line.

The bolts also need to be tight in the holes (as in drive them in tight) for best performance and load carrying.

Using bolts (and even nails) to make load rated joints is not as simple as it looks.
The type of wood also greatly affects the fastener schedule (number and spacing).

I dunno mongrel, if the ceilings are tall enough, why can't he add the girders, then add non-load bearing cross pieces, cover it all in finish lumber to make a pretty coffered ceiling? Maybe your idea could work in a living space after all. Some of the prettiest things in old buildings were born out of structural necessities. I remember the first time I understood the purpose of flying buttresses, I was delighted that they weren't just "for fancy".

I just love it when you, worthy, and brick get chatting. Worlds within worlds. There is never an end to what you can learn about houses. (and I'm being sincere, not sarcastic) Brick, that bit about how to stagger fasteners depending on the grain of the wood--makes perfect sense! But would I have figured it out on my own without breaking something first? Probably not!

My retraction is based on my experience that nobody loved a dropped girder off-center in their living room ;-)
We are usually directed to do flush girders, and with this kind of "mess" that's not an option. And "since it's lasted this long"(tm) unless there's red flags indicating failure, a cautious and cost-effective approach would be to add more fasteners as insurance.
Casey

Hi Boys,
Sorry about that, I sort of just dropped off the face of the earth for a bit.
I appreciate all the thoughts, especially enjoyed looking a little bit on "the devil queen" (although a little too close to home).
After spending some time looking into the suggestions and armed with an old engineering book from the 70's which specifically talks about this type of joist scenario I went down to visit the Inspector. Of course I had a rough sketch with me as well. Basically what it has boiled down to is the following pcs.
(a) its an old house with old wood which is well over-sized joists for the spans.
(b) there is no deflection with 1400 sf of 3/4" wood flooring sitting directly above the splices.
(c) there is not any real vibration when a 200lb beast jumps heavily above them.
(d) the nailing scedule on the splices is good-although I am adding a couple bolts on each.
(e) I will be adding solid cross bracing in such a way as to ensure the splices can not twist or separate.
(f) these joists only support a bedroom floor
(g) I am not making any substantive changes to the location and loading of the bearing walls.
Given these considerations he was comfortable giving the green light for the specific installation.

For those of you who might be interested in finding more information about this type of joist solution try looking in:
'75 copy of "wood frame house construction" USDA, Forest Service, Ag Handbook #73 under the "in-line joist system"
Additionally you might be interested in researching the condition called "beam overhanging support"

What it functionally ends up being is a uniformly loaded cantilevered beam with a small point load at the end, with the exception of the size of point load it is not at all unlike a cantilever with a load-bearing wall which is commonly accepted today.

Thanks again for the input. It really does help to talk with your inspector without seemingly like a know-it-all or looking like an unprepared moron.