My wife and I bought an old... really old... house and have begun totally gutting/updating everything. After ripping out all of the old lath and plaster, we found a feature in the outside walls I have never seen before. The house is balloon-framed with full dimensional lumber, which is familiar... but we found a second layer of tongue and groove siding material in the middle of every stud bay. A nailing strip was added to every stud, and a stack of boards spanned between them, beginning at the bottom and going all the way to the top of the wall. We assumed this was done to create a second air pocket within the wall to help insulate... but as I was removing some of this material I began wondering if it might have been added as resistance to racking, since sheet goods weren't available back then. The wall had lath and plaster on the inside, and a layer of 3/4" lap siding on the outside... and this in the middle.
Has anyone ever seen this before? Any ideas on what it was for? I tried posting pictures but the site kept telling me they weren't valid file types... even thought they are jpg. Thanks for any help.