Thanks again Jacon4 !! Did not think about on-site construction but that makes sense !! Perhaps this belonged to a lawyer and built to hold heavy law books ??
You occasionally run into construction techniques that are joined with pegs but its less common that the typical dovetail joinery !!
Jacon4 is an expert on Early American furniture and the best I know on construction methods prior to 1900 !! Just thought I would get an opinion from an expert on your bookcase !! The size and weight of the materials used to build the bookcase threw me for a while !! But I did not think about the obvious !! That it was built on site for a large house !!
And as Jacon4 said,, value is likely to be less that you think !! Especially for something of this size !! Victorian furniture has taken a nose dive in last 10 years !! No one wants the old dark furniture anymore !! If it were me and I wanted to sell it I would start with your local Craigslist !! Or try a consignment at a good antique shop or mall !! Here in my area(Texas) it would bring somewhere between $500. and $700. depending on location !! Generally metro areas would be on the higher end and more rural areas closer to the $500. range !! You should research values for your specific area !! Might sell higher where you are !! Values are not the same nationwide !!