Counties of Virginia are divided into magisterial districts, the number of districts varying from three to ten. Provision is made in the state constitution that additional districts may be made by law only if the new district contains at least 30 square miles. Each district has one supervisor elected by the qualified voters. Thus, the Board of Supervisors of the county consists of one representative elected from each magisterial district in the county with the exception of Arlington County where the Board of Supervisors is elected at-large from the county. Therefore, the number of members of each Board of Supervisors varies among the counties. A chairman for this group is selected by the members themselves. Their meetings are usually held once a month at the Court House located at the County Seat. The Board of Supervisors carries out various duties such as: (1) supervises county affairs, (2) establishes and levies county taxes, (3) prepares the county budget, (4) audits claims against the county, (5) erects and maintains county buildings, (6) acts as a legislative and executive body by issuing and carrying out ordinances on such subjects as sanitation, health and police, (7) approves saluary scales for county workers, (8) controls county property, (9) furnishes care for the mentally and physically handicapped, and (10) borrows money. There are five county officials of importance who are elected to office by the qualified voters on the first Tuesday after the first Monday in November and take office on January 1 following their election. These officials are: (1) Attorney for the Commonwealth--a lawyer who acts as a legal adviser to the Board of Supervisors and to the county officials and who acts as legal representative of the people of the county; he also acts as prosecutor for all civil and criminal cases in which the county is interested; he is elected by the qualified voters for a four-year term. (2) County Clerk--an officer who serves as a clerk to the County Board of Supervisors and to the County Circuit Court; as the main county recording official, he records all types of county documents (such as deeds, wills, judgments, mortgages, births, divorces, deaths, elections, court trials and marriages); attends meetings of the Board of Supervisors and has custody of property records; he is elected by the qualified voters for an eight-year term. (3) Commissioner of the Revenue--an official who assesses property values for taxation purposes, assesses State personal income taxes, prepares personal property tax books and land books and assesses and collects all professional and business licenses; he is elected by the qualified voters for a four-year term. (4) County Treasurer--an officer who collects the county taxes assessed by the Commissioner of Revenue, collects the state taxes, keeps the county funds and disburses money upon order of the Board of Supervisors; he is elected by the qualified voters for a term of four years.