here also the ploughgate was the fourth part of a Davach, and consisted of five homesteads; on the other hand, we are told that each township in Isla consisted of two and a half merk lands.[274] The state of these districts probably gave the Davachs and penny lands a fluctuating value, which depended more upon the pasture and the stock it carried than on the arable land. There is an old tradition that the Davach was land capable of pasturing 320 cows, and that a merk land was as much land as would graze twelve milch cows, ten yeld cows, including three-year-olds, twelve two-year-olds, twelve year-olds, four horses, four fillies, mares and followers, one hundred sheep, and eighty goats.[275] The two systems of land measure appear to meet in Galloway, as in Carrick we find the measure by Penny lands, which gradually become less frequent as we advance eastward, where we encounter the extent by merks and pounds, with an occasional appearance of a penny land, and of the Bovate or oxgang in Church lands. [Sidenote: Burdens on the land.] The burdens upon the land held by the community in Scotland seem to have been principally four. We find them still attaching to the Crown and the Church lands during the twelfth and thirteenth centuries, and they are analogous to those connected with the Irish tribe system. They were _Cain_, _Conveth_, _Feacht_, and _Sluaged_. The two former were fixed payments in kind. The two latter were services to which the possessor of the land was subject. They are rendered in Latin by the words _expeditio_ and _exercitus_. We find these burdens in both of the leading divisions of the country north of the firths. Thus, by a deed dated at Lismore in the year 1251, Sir Ewen, son of Duncan de Erregathil (Argyll), granted to William, bishop of Argyll, fourteen penny lands in Lismore, free of all secular exactions and dues—viz., _Cain_, _Coneveth_, _Feacht_, _Sluaged_, and _Ich_—and of all secular services;[276] and similarly Roger, bishop-elect of St. Andrews, granted between 1188 and 1198, when he was consecrated, the lands of Duf Cuper to the church and canons of St. Andrews, free of ‘_Can_ et _Cuneveth_ et exercitu et auxilio et ab omni servicio et exactione seculari.’[277] [Sidenote: The _Cain_ or _Can_.]