Polychronicon Ranulphi Higden maonachi Cestrensis; together with the English translations of John Trevisa and of an unknown writer of the fifteenth century.
Higden, Ranulf, d. 1364., Trevisa, John, tr. d. 1402., Caxton, William, ca. 1422-1491., Malverne, John, d 1415?, Babington, Churchill, ed. 1821-1889,, Lumby, J. Rawson ed. (Joseph Rawson), 1831-1895.
Page  49, vol.2

Of the famose floodes in hit. Capitulum quadragesimum sextum.

Alfridus. Thre famose floodes floo thro Briteyne, to whom and thro whom marchandise commethe allemoste from alle naciones and regiones by schippe, whiche be Thamys, Seuerne, and Humbre, whiche waters departe three princi|palle prouinces as thre realmes, that is to say, Englonde, Wales, and Northumbrelonde. ℞. Thamisia, whiche is callede Temmys, semethe to be compownde of ij. waters, whiche be callede Thamia and Isa. That streme callede Tame rennenge by Dorchestre fallethe in to Ise, þerfore alle that water rennenge soe togedre is called Tammyse. Page  51, vol.2Willelmus de Pontificibus, libro secundo. The water of Tham|myse takenge the originalle of hit nye to Tewkesbury of a lytelle welle, floethe by Oxforde, London, vn to the haven of Sandewiche, goenge þer in to the este see, reteynenge the name of hit paste London by xlti myles, whiche was somme tyme as a cause terminative of men of Kente, of Este Saxones, West Saxones, and of men of the Marches. Seuerne, a floode of Briteyne, is callede Habren, of Habren doȝhter of Estrilde, whom a qwene callede Guendolena drownede in hit, but now hit is callede Sabrina, by the corrupcion of the langage of Latyn. That water of Seuerne begynnethe in the myddes of Wales, and goethe firste towarde the este vn to Schrewisbury, after that hit turnethe in to the sowthe to Brugges, Worchestre, and to Glocestre, fallenge in to the see at Bristowe, whiche was somme tyme a terme of Englonde and of Wales. Willelmus de Pontificibus, libro quarto. Seuerne is a perellous streme fulle of fische, in whom is such a movenge that hit turnethe vp the grauelle from the bothom of the water, and makethe theyme in a grete hepe Page  53, vol.2 oftetymes goenge ouer the brynkes of hit. Also that water callede Humbre toke the name of Humber kynge of Hunes drownede in hit. Whiche rennethe*. [Probably rennenge is the true reading.] firste in the maner of a bawe from the sowthe parte of Yorke to the prouince Lindescience, whiche longede somme tyme to the Marches, dothe diuide Northumbrelonde from that other plage; whom the floodes of Trente and of Ouse fallenge in to hit*. [cause hit MS. (first hand.)] cause to be encreasede gretely thro them.