USCG1986
They make a little device they call a Vin-O-Meter. It uses a capillary action to measure
concentration of alcohol. Mine seems quit accurate. Ebay and other sell them for 5 or 6 bucks. Needless to say, The wine needs to be clear as any particles will plug the small capillary.
I recently made this and am quit happy with it.
I used 4 gal Tree Top Apple Juice and 1 gal of Sams Choice Spiced Apple Cider.
The Sams has a lot of pulp but a nice Cinnamon flavor.