Sheriffs also collected the levies which financed county government. However, being subject to the pressures of their own circumstances, there often was a tendency to give first priority to activities which brought in their own fees. This led the General Assembly to require that sheriffs collect public levies before they take any fees for themselves, and to prescribe a number of other rules for improvement of the conduct of their offices.[55] The role of the sheriff in the tax collection process always was a difficult one. The procedure for financing the county, initially, was for the justices simply to compile lists of their expenses and the freeholders of the county, compute how much was needed from each freeholder to cover the cost of government, and direct the sheriff to collect it. When the sheriff made his return to the court he was entitled to deduct a percentage as his commission.[56] However, revenue was often not collected, either because the job was farmed out to others who defaulted, or the county was too poor, or its residents were scattered and could not be found.[57] These problems ultimately led the General Assembly to establish other officers whose exclusive duties were the levying and collecting of revenue, but throughout the seventeenth and eighteenth centuries the sheriff performed a central role in the revenue process. The sheriff was also the custodian of the county jail and its prisoners. He had the authority to decide on and collect bail, and he was liable for a fine if a prisoner escaped. He appears generally to have taken his responsibility for the county jail lightly, for there is evidence of widespread contracting for others to provide the guard for the jail and the food for the prisoners. Other officials who were part of the colonial county government performed specialized functions, but unlike the clerk and sheriff, took no part in the general administration of county business. The office of county surveyor was created early in the seventeenth century to meet the obvious need for accurate measurement and recording of land. Initially, the surveyor was appointed by the county court, and sometimes treated as an additional duty of the clerk or sheriff. However, by the end of the eighteenth century a significant change had occurred in the legislation which called for appointment by the governor after a candidate had been examined and approved by the faculty of the College of William & Mary. By 1783, therefore, the surveyor became the first county official to be required to show professional competence as a condition of appointment.[58] The office of constable appeared in 1645, and may be described as similar to that of sheriff, except that it served the court of a single justice.[59] Constables were appointed by the justices of the county court and served in precincts delineated by the justices.