Crush the garlic with the blade of a knife. Chop the apples, and simmer both ingredients in the water until soft. Strain through a jelly bag suspended over a large bowl. Measure the juice collected, and pour it into a large saucepan. For every 3 pt / 1.70 l juice, stir in 2 lb / 900 g sugar. Heat gently until the sugar has dissolved, and then boil hard until setting point is reached. While the mixture is boiling and before it reaches setting point, add the strained lemon juice. Pot the jelly in small, clean, hot jars. Cover with wax discs and seal with cellophane covers. Label the jars.