The exact meaning of magistrate varies widely depending upon the context. For example:
in the U.S. federal court: assists district court judges by handling minor offenses or administrative tasks such as preliminary hearings (often referred to as a magistrate judge rather than just a magistrate)
in some U.S. states: a judge in the state court
in France, Belgium, Italy, the Netherlands, and other civil law countries: a sitting magistrate is a judge and a standing magistrate is a prosecutor
in England: may be a volunteer without formal legal training who performs a judicial role with regard to minor matters
in ancient Rome: a powerful officer with both judicial and executive power
To beard a magistrate in his stronghold, and on the Sabbath, too!
Chapter 6 (72% in)
Mr. Linton was a magistrate, and though he had fifty wives dead, he should inquire into this.
Chapter 17 (50% in)
Grief, and that together, transformed him into a complete hermit: he threw up his office of magistrate, ceased even to attend church, avoided the village on all occasions, and spent a life of entire seclusion within the limits of his park and grounds; only varied by solitary rambles on the moors, and visits to the grave of his wife, mostly at evening, or early morning before other wanderers were abroad.
Chapter 17 (76% in)
There are no more uses of "magistrate" in Wuthering Heights.