This section is from the book "Preserving And Pickling", by Mary M. Wright. Also available from Amazon: Preserving and Pickling: Two Hundred Recipes for Preserves, Jellies, Jams, Marmalades, Pickles, Relishes and Other Good Things.
This jelly may be made by using the parings of both the quinces and apples that were used in making preserves with a little more of the whole fruit added. Cut up the quinces and apples that are to be used, and add to the parings, then cover with water and simmer very slowly until the fruit is tender. Fill into a jelly bag, and allow to drip into a vessel, without pressing. Pour the juice into a preserving kettle, measuring it first, and allowing three-quarters of a pound of sugar to each pint of juice. Boil the juice about fifteen minutes before adding the sugar, which should be heating in the oven. After the sugar is added bring to a boil, and then test on a saucer.
When it jellies fill into glasses; if not, boil a few minutes longer, testing it frequently, for as a rule quince juice jellies very quickly. This makes a beautiful clear, light jelly, with a mild, delicious flavor.