A glance at the accompanying Enclosure Map of England will indicate the importance of common fields in the social life of rural England at certain dates. It was prepared in the following manner: On the Ordnance County diagrams each parish which had an Enclosure Act by which common field arable was enclosed was coloured; if the Act was passed between 1700 and 1801 it was coloured yellow; if passed after the general Enclosure Act of 1801 and before that of 1845, it was coloured green; if after 1845, purple. A map of England was drawn summarising the results of the county maps. On this _at least_ all purple patches showed parishes which possessed open field arable in 1845; _at least_ all the green and purple area combined indicated parishes which had open field arable in 1802; _at least_ all the coloured area had open field arable in 1700. In the printed map these colours are represented by three forms of shading. Of the unshaded area one can simply say that the Enclosure Acts throw no light upon its agricultural history so far as the land under tillage is concerned. To a very great extent it was undoubtedly being enclosed otherwise than by Act of Parliament simultaneously with the progress of Parliamentary enclosure, but to a still greater extent it either never passed through the common field system or was enclosed before 1700. This statement raises questions which are dealt with below. For the present I have to deal with the general history of those parishes which did pass through the common field system. The original Board of Agriculture, which was an association on similar lines to those of the Royal Agricultural Society, but enjoying a grant from the Treasury, was founded in 1793, with Arthur Young as secretary and Sir John Sinclair as president. It immediately took in hand the work of making an agricultural survey of Great Britain, county by county. Some counties were surveyed several times, but the original survey of England was completed in the years 1793 and 1794. William Marshall, the ablest agricultural writer of the time, single-handed accomplished an agricultural survey of England, ignoring county divisions and dividing the country according to natural divisions marked by similarity of soil, crops and agricultural methods. The two surveys together give us ample information on the different methods of cultivating open or common fields at the end of the eighteenth century. On the whole, the most general system, particularly in the midland counties where common fields remained most numerous, was the following form of the three-field system:--