na_, one _Deudone, the son of Samuel_, and one _Aaron_.
Some of their monetary transactions are recorded in the "Rotulus
Cancellarii vel Antigraphum Magni Rotuli Pipae de tertio anno Regni Regis
Johannis" (printed under the direction of the Commissioners of the Public
Records in 1863, p. 96), and we have here not only their names as evidence
of their Jewish origin, but they are actually spoken of as "_praedictus
Judens_." Their transactions, however, are purely financial, and do not
lead us to suppose that the Jews, in order to make tin, condescended, in
the time of King John or at any other time, to the drudgery of working in
tin-mines.

_July_, 1867.

XV. THE INSULATION OF ST. MICHAEL'S MOUNT.(89)

St. Michael's Mount in Cornwall is so well known to most people, either
from sight or from report, that a description of its peculiar features may
be deemed almost superfluous; but in order to start fair, I shall quote a
short account from the pen of an eminent geologist, Mr. Pengelly, to whom
I shall have to refer frequently in the course of this paper.

"St. Michael's Mount in Cornwall, he says, "is an island at very high
water, and, with rare exceptions, a peninsula at very low water. The
distance from Marazion Cliff, the nearest point of the mainland, to
spring-tide high-water mark on its own strand, is about 1680 feet. The
total isthmus consists of the outcrop of highly inclined Devonian slate
and associated rocks, and in most cases is covered with a thin layer of
gravel or sand. At spring-tides, in still weather, it is at high-water
about twelve feet below, and at low-water six feet above, the sea level.
In fine weather it is dry from four to five hours every tide; but
occasionally, during very stormy weather and neap tides, it is impossible
to cross from the mainland for two or three days together."

"The Mount is an outlier of granite, measuring at its base about five
furlongs in circumference, and rising to the height of one hundred and
ninety-five feet above mean tide. At high-water it plunges abruptly into
the sea, except on the north or landward side, where the granite comes
into contact with slate. Here there is a small plain occupied by a
village.... The country immediately behind or north of the town of
Marazion consists of Devonian strata, traversed by traps and elvans, and
attains a considerable elevation."

At the meeting of the British Association in 1865, Mr. Pengelly, in a
paper on "The