is applicable to an island that adheres to the river bed, not to one kept in place by  vegetation. If the island is a circular one it will be difficult to measure it. But this is  clear, that everything nearer my land falls to me and so what is nearer my neighbour  will fall to him. This rule will never fail. These observations are not applicable in  the case of agri limitati, for there the right of alluvion has no place. Agri limitati  are those assigned in certain localities and by fixed boundaries so that it may be  known what was given to each and what retained and left [in public ownership].  Nor does an island in a public stream cede to the nearer riparian owner if the lands  concerned are agri limitati; it belongs rather to the first occupier,10 and consequently  to the king by virtue of his privilege. 11The same kind of accession is  applicable to the bed of a river which has been left dry; the old channel belongs to  the riparian owners in proportion to their respective frontages on the stream. The  new channel, however, begins to have the same legal character as the river itself,  that is, a public character. For the river by forming a new channel makes private  land public and public land private. Thus rivers are said to discharge the function  of magistrates, that is, of judges or princes. For a judge or emperor often adjudges  what belongs to one to another, justly or unjustly, in good faith or bad. Where a  river has taken my land from me by the formation of a channel and afterwards  returns to its former channel, in strict right I can claim nothing in the land formerly  mine. It belongs to those who have lands along the banks. But this is hardly  equitable and would not be enforced. Where the stream has not formed a new  channel in my land but simply overflowed it, its identity is not changed nor its  ownership in any way altered.12
Of accession made by human action, by joining together materials.
 13So much of accession produced by the operation of natural forces alone. There is  another kind, produced by the act of human beings alone, effected by joining one  thing of the same or a different kind to another, by soldering or by melting  together, as may be read in the Institutes,14 and it is there explained which part  ought to cede to the other. If the things are joined by soldering, the lesser accrues  to the greater or more valuable; if neither is more valuable, each owner will recover  his own. The right of accession by the labor of human beings is also applicable to  buildings, as