On the one hand, then, it is obvious that the great inequality of the holdings held by servile and semi-servile tenures from the time of Domesday onwards, was favourable to the creation of the conditions necessary to make piecemeal enclosure difficult. The _socmanni_ or _francigenae_, who held a whole carucate or ploughland apiece, presumably also had, as a rule, a whole ploughteam, and were able to plough for themselves, while their neighbours, who held yardlands and half-yardlands, _i.e._, one-quarter or one-eighth of a ploughland, could only have their lands ploughed by the common village ploughs. As soon as the _socmanni_ and _francigenae_ began to permanently improve the soil, as for instance by marling, the beneficial results of which were believed in the eighteenth century to last for at least twelve years, they would naturally become a practically insuperable obstacle not only to any re-division of the land, but also to any minor variation in the exact position of the ridges which comprised the different holdings. Once one such holding was definitely located, the fixing of all other holdings which were intermixed with it would follow: every increase of certainty would be an encouragement to any given tenant to improve his land, and every expenditure of effort by a tenant on permanent improvement would be an additional motive to him to resist any changes in the position of his ridges. On the other hand, in the case of land first brought into cultivation at a later date, when servile tenures had become obsolete, by “tenants at will” of the lord of the manor, the assured continued occupation of a defined set of ridges in land so reclaimed would not arise, even if the original tenants practised co-aration; and if the original cultivators worked independently, of course no intermixture of holdings would ever arise on such holdings. Hence the very close connection between copyholds, _i.e._, the commuted servile tenures, and common fields, which was observed as long as common fields were numerous.