There is hardly a book on Cornish history or antiquities in which we are not seriously informed that at some time or other the Jews migrated to Cornwall, or worked as slaves in Cornish mines. Some writers state this simply as a fact requiring no further confirmation; others support it by that kind of evidence which Herodotus, no doubt, would have considered sufficient for establishing the former presence of Pelasgians in different parts of Greece, but which would hardly have satisfied Niebuhr, still less Sir G. C. Lewis. Old smelting-houses, they tell us, are still called _Jews’ houses_ in Cornwall; and if, even after that, anybody could be so skeptical as to doubt that the Jews, after the destruction of Jerusalem, were sent in large numbers to work as slaves in the Cornish mines, he is silenced at once by an appeal to the name of _Marazion_, the well-known town opposite St. Michael’s Mount, which means the “bitterness of Zion,” and is also called _Market Jew_. Many a traveller has no doubt shaken his unbelieving head, and asked himself how it is that no real historian should ever have mentioned the migration of the Jews to the Far West, whether it took place under Nero or under one of the later Flavian Emperors. Yet all the Cornish guides are positive on the subject, and the _primâ facie_ evidence is certainly so startling that we can hardly wonder if certain anthropologists discovered even the sharply marked features of the Jewish race among the sturdy fishermen of Mount’s Bay. Before we examine the facts on which this Jewish theory is founded,—facts, as will be seen, chiefly derived from names of places, and other relics of language,—it will be well to inquire a little into the character of the Cornish language, so that we may know what kind of evidence we have any right to expect from such a witness.