So, in case of fire from negligence in a tref, the holder of the house in which it arose was to pay for the damage to the next houses on each side if they took fire.[34] And again no indemnity was to be paid to the owners in a trefgordd for damages from the fire of a smithy if covered with shingles or tiles or sods, nor from the fire of a bath, provided always that the smithy and the bath were at least seven fathoms from the other houses in the trefgordd.[35] [Sidenote: Not always of one gwely only.] The description above quoted of the normal trefgordd suggests that the herd under the one herdsman did not belong to one person or homestead, but to many; and so far it seems to be consistent with the surveys which represent the villatæ as occupied by the cattle of several family groups who had grazing rights therein. And this, too, accords with what the Denbigh Extent tells us of the individual tribesmen, viz. that only some of them had homesteads. So-and-so ‘habet domum’ or ‘non habet domum.’[36] The young tribesman with his _da_ thus may have joined in a common homestead with some one else--probably with his parents or near relatives. Distinguishing, then, the tref as a taxable area from the trefgordd, and still confining attention to the trefgordd as a cluster of homesteads united for the practical purpose of occupation, let us recur to the things which bound the trefgordd into one group, viz. the one plough, the one oven, the one churn, the one bull, and the one herdsman. Here are the two elements combined of pastoral and agricultural co-operation, and the trefgordd is the local and physical unit of this co-operation. [Sidenote: The unit of co-operative dairy farming. The common herdsman and his dog.] Taking first the pastoral element, the trefgordd was a working unit of co-operative dairy-farming. The cattle of several households or individuals were put together in a common herd with a common bull and under the care of a common herdsman (bugeil) and his dog. It may be regarded as a group of the homesteads of the persons in charge of such a herd, and the tribesmen of a gwely may have cattle in the herds of more than one trefgordd. Three things were ‘ornamental’ to a trefgordd, ‘a book, a teacher versed in song, and a smith (gov) in his smithy;’ but a trefgordd herdsman was an ‘indispensable’ of the _hendrev_,[37] and, when engaged with his herd in summer on the mountain, _his_ ‘three indispensables’ were ‘a bothy, his herdsman’s dog, and a knife;’ and the three indispensables of his bothy were a roof-tree, roof-supporting forks, and wattling, and he was at liberty to cut them in any wild wood he pleased.[38] So far, then, as the pastoral element was concerned, the trefgordd was occupied by a little group of tribesmen engaged in dairy-farming having charge of cattle in a common herd, with a common bull, and under the care of a common herdsman and his dog. [Sidenote: The herd of 24 kine.]