... Cavall—the "hound of deepest mouth," for whose baying, as the Laureate tells us, Guenever listened as she halted with Geraint on the knoll above the water of Usk.  Very famous was Cavall, and numberless his deeds of "derring do" in pursuit of wolf, boar, and red deer.  Whilst hunting the "wild boar of Troynt," Cavall left the print of his paw on a certain rock, which afterwards became as famous throughout Breconshire as St. Mildred's footprint in the Isle of Thanet, or the hoofmark of Mahommed's camel at Mecca.  King Arthur caused a heap of stones to be piled about the rock—itself a loose fragment:—for, said the legend, if it was carried off to any distance, it was sure to be found in its old place on the following morning... (London Quarterly Review, 1861)

    The learned Camden, referring to the oldest mottoes he ever met with, mentions the old seal of Sir Thomas Cavall, who bore for his arms a horse, and for his motto, "Thomae credite, cum cernitis ejus equum."
    As the name is derived from Caballus, I suppose the correct way of spelling to be Cabal or Caball, Cabel or Cabell; but I have found it spelled in almost every conceivable way:  Cabble, Cable, Cabel, Cabell, Cabbel, Cabbell, Cabal, Caball, Cabbal, Cabball, Cabyll, Cabbil, Caable, Cabul, Cabull, Chaable, Cavall, Cavel, Capel, Capell, Caple, Cabelle, etc.; Kaable, Kable, Kabell, Kabel, Kabbel, Kebel, Kebell, Kebyll, Keble, Kebble, Kebbel, Kebbell, Keeble, Kyble, Gabble, Gabbell, Gable, etc., etc.  In French, I find the names Cabal and Cheval; in Spanish, Caballero and Cavallero; in Dutch, Cabel and Kabel; in Italian, Caballero, Caballinus, Caballis, Caballo, and Caballus; and in Genoese, Caballo.  In a list of foreign Doctors of the 16th century, I find the following:  Francesco Caballo or Caballus, Italian physician and medical writer, died 1540; Guillaume [William] Cappel [Cabell?], French Doctor of Medicine, born 1530; and Pierre Cabal, French surgeon and writer, who flourished in 1570. (The Cabells and Their Kin, Brown, 1895).