How to insulate 1870 house indoor windows with decorative trim?

Hi Virginia. Are you windows double hung? Are there two sashes? If so (which is probably true) you could consider doing what we did with one of our living room windows. The first picture is of the window "stop" see the screw? There are four screws on these window stops in our house. They allow the window sashes to be removed in case the weight cords have broken. Anyway we decided that even though we have storm windows on our l.r. window we did not need to use this window (open it) so we added a sheet of plastic over the whole window. You really can't see it but it is there and since this is the n/e corner this could be a cold room. What we did was remove the stops (by unscrewing the screws) then we stapled the plastic in place over the entire window. It has been more than 10 years that we have had this. I have windexed this plastic and sort of treat it as a window. You could only do this on windows that you don't need to open. It is inexpensive (no kit, just plain heavy plastic) can't be seen and is another barrier to cold. Also fleece makes a very good insulator and I have lined some floor length curtains with it, simply by pinning it in place at the top. Good luck!