The commissioners of supply were instituted by Act of Convention in 1667 initially to assess and collect the land tax from each landowner, based on the value of their estates. They dealt with many other concerns too on a county-wide basis, including providing a police force and appointing county officials. They were drawn mainly form the landowning class but employed assessors, collectors and clerks each year, usually local people, to do the land valuation. This was carried out each year and was used to calculate the amount of land tax, or cess, to paid to the king, being of a certain proportion for each pound 100 Scots money of land value. It was also used to work out the public burdens, such as schoolmasters salary, teinds and stipend for the parish minister, to be paid each year. There were also valuation thresholds for commissioners of supply, freeholders, roads trustees and for commissions in the army, navy and local militia. The minutes of the commissioners consist largely of disjunctions, or apportioning of valuations between lands of the estate of one landowner; he might want each part valued separately in order to create nominal freeholders to gain fictitious votes. The apportionment could be agreed upon by the parties involved and ratified by the commissioners, or an inquiry might need to be held, examining witnesses. The commissioners later became involved with the collection of others taxes, on windows, hearth, carriages, horses, servants and property. The commissioners continued to exercise their various roles until the institution of county councils in 1889. The following year saw the last intervention of the commissioners in the land tax.