Prepare pears by running under cold water, draining, coring and finely chopping them. Add 3 cups water. Simmer 10 minutes, covered, stirring occasionally. Place prepared pears in dampened jelly bag or several layers of dampened cheesecloth. Let juice drip, undisturbed, for at least 2 hours or overnight. Note: Squeezing the jelly bag may cause jelly to be cloudy.

Prepare boiling water canner. Heat jars in simmering water until ready to use, do not boil. Wash lids in warm soapy water and set aside with bands.

Measure juice and other ingredients. If you need more juice, simply add water to fruit pulp and extract.

Combine prepared pear juice with lemon juice in a 6-or 8-quart saucepan. Gradually stir in pectin. Add up to 1/2 tsp. butter or margarine to reduce foaming, if desired. Bring mixture to a full rolling boil that cannot be stirred down, over high heat, stirring constantly.

Add entire measure of sugar, stirring to dissolve, Return mixture to a full rolling boil. Boil hard 1 minute, stirring constantly. Remove from heat. Skim foam if necessary.

Ladle hot jelly into hot jars leaving 1/4 inch headspace. Wipe rim. Center lid on jar. Apply band until fit is fingertip tight. Place the jar in the boiling-water canner. Repeat until all jars are filled.

Water must cover jars by 1 inch. Adjust heat to medium-high, cover canner, and bring water to a rolling boil. Process half-pint jars 10 minutes, adjusting for altitude. Turn off heat and remove cover. Let jars cool 5 minutes. Remove jars from canner; do not retighten bands if loose. Cool 12-24 hours. Check lids for seal, they should not flex when center is pressed.