the Urim and the Thummim

I looked in my “Nelson’s New Illustrated Dictionary”, and this is what it said about the Urim and Thummim (YOU rim, THUME em)…

Urim and Thummim—gems or stones carried by the high priest and used by him to determine God’s will in certain matters. Many scholars believe these gems were lots that were cast, much as dice are thrown, to aid the high priest in making important decisions.
The Urim and Thummim were either on, by, or in the high priest’s breastplate. For this reason the breastplate is often called the breastplate of judgment, or decision. In the instructions for making the breastplate, the linen was to be doubled to form a square (Ex. 28:16). If the top edge was not stitched together, the breastplate would be an envelope, or pouch. Many scholars believe the Urim and Thummim were kept in this pouch and were stones or gems with engraved symbols that signified yes or no or true-false. By these the high priest reached a decision, according to this theory.
The Jewish historian Josephus (about A.D. 37-100), a contemporary of the apostle John, believed that the Urim and Thummim had to do with the flashing of the precious stones in the breastplate. Later Jewish writers believed that the letters in the names of the twelve tribes of Israel engraved on the stones stood out or flashed in succession to spell out God’s answer. This theory does imply that the Urim and Thummim could produce answers to questions that called for more than a mere yes or no reply. Another theory is that by staring at the Urim and Thummim the high priest went into a state of ecstasy or trance during which God spoke to him.
The student or Bible teacher should bear in mind that all of the theories are pure guesswork. No one knows the exact nature of the Urim and Thummim or precisely how they were used.
There are few allusions to the Urim and Thummim in the Bible. They are first mentioned in the description of the breastplate of judgment (Ex. 28;30; Lev. 8;8). When Joshua succeeded Moses, he was to have answers from the Urim through Eleazar the priest (Num. 27:21). They are next mentioned in Moses’ dying blessing upon Levi (Deut. 33:8). There are places in the Bible where Urim and Thummim may be implied but are not named (Josh.7:14-18; Sam. 14:37-45; 2Sam. 21:1).
Saul sought direction from the witch of Endor when he could receive no answer from the Lord, “either by dreams or by Urim or by the prophets” (1Sam. 28:6). Another interesting reference to the Urim and Thummim occurred during the period after the return of the Jewish people from their years in captivity by the Babylonians. The Persian governor of Jerusalem denied the people permission to observe some of the ancient Jewish food laws unt8il “a priest could consult with the Urim and Thummim” (Ezra 2:63).