The Secretary of Agriculture separately, or jointly with the county commissioners of any county, is hereby authorized by contract, or otherwise, to cause to be prepared for the use of his department, and such other departments and agencies of the State Government as may have use for the same, a rural index map of the several counties of the Commonwealth. Such maps shall be prepared on such simple arrangement or system as will readily locate, by direction, distance, and road or highway, from the principal community centre, each rural residence in the county. The said secretary may also place at each such rural residence an appropriate sign showing the location thereof by direction and distance from the community centre.