Bilberries.
Bilberries do not keep many weeks, but are very much liked for tarts.
Pick them carefully, and put them on the fire in a preserving pan without any water as they are very juicy. For each 1 lb. of fruit give ½ lb. of sugar. Let them boil ½ hour, then tie them up in jars. When you make the tart add a tablespoonful of Black Currant Jelly, nor jam (see Jams, Jellies, &c.), to improve the flavour.
Mrs. Davidson says they keep well if you allow 1 lb. of sugar to 1 lb. of fruit, and boil ½ hour—otherwise they turn sour.