I have a house built in the late 1890's the roof rafters do not have a ridge board. There are a number of "braces" about every ten feet - one end attached to the bottom of the rafter above where the bottoms rest on the ridge board/s atop the perimeter brick walls. These braces are actually pieces of the boards used for the sub floors(approx 1" x 5" about every 8 feet or so). with the other end square nailed in the respective floor joist. There does not seem to be any tension on these boards. Can they be removed or do they really have a purpose. I think the were there originally when the roof was being installed but now, the weight of the roof and the decking made of 1 x 5 (rough sawn, of course) is sufficient. Opinion????